SKA antenna phase center precision measurement calculation adjustment method

Abstract

The invention discloses an SKA antenna phase center precision measurement calculation adjustment method, and relates to the technical field of antenna measurement. The method is realized based on a photogrammetry system, 16 feed source tools and a Stewart mechanism, firstly, a theoretical coordinate system of an SKA antenna feed source and an SKA antenna phase center is calculated, an actual coordinate system of the SKA antenna feed source and the SKA antenna phase center is obtained according to measurement of the photogrammetry system on the 16 feed source tools, and then the SKA antenna feed source and the SKA antenna phase center are calculated according to a difference value between the theoretical coordinate system and the actual coordinate system. And a Stewart mechanism is adopted for adjustment until the phase center of the SKA antenna is accurately adjusted. After the antenna phase center measurement calculation adjustment method is adopted, the antenna phase center measurement adjustment efficiency is improved by 5 times, and the antenna phase center pose precision is improved by more than 10 times. The antenna phase center measurement calculation adjustment method is simple, high in efficiency and easy to implement.

Description

Technical Field

[0001] The present invention relates to the field of antenna measurement technology, and in particular to a method for precisely measuring, calculating and adjusting the phase centroid of a SKA antenna. Background Art

[0002] The antenna phase center is the electromagnetic wave radiated by the antenna. After leaving the antenna for a certain distance, its equal phase surface will be approximated as a sphere. The center of the sphere is the equivalent phase center of the antenna. In the design of efficient antennas, it is generally required that the antenna phase center can be accurately measured, and it is also required to be able to be precisely adjusted to meet the requirements of antenna performance design. In the process of antenna manufacturing and installation, there is inevitably a phase center posture deviation. With the increasing requirements for antenna performance indicators, the demand for precise measurement and precise adjustment of the antenna phase center is becoming more and more urgent. Therefore, it is of practical significance to design a high-precision measurement, calculation and adjustment method for the antenna phase center posture.

[0003] At present, the antenna phase centroid measurement, calculation and adjustment method mainly adopts the method of back calculation of the antenna feed sleeve structure and adjusting the angle through gaskets. Not only is the measurement accuracy low and the calculation method has large errors, but the adjustment is also inaccurate and inefficient. Summary of the invention

[0004] In view of this, the present invention proposes a method for precise measurement, calculation and adjustment of the phase center of the SKA antenna. The method is applicable to precise measurement, calculation and precise adjustment of the phase center of the dual-bias antenna, especially the SKA antenna. After adopting this method, the accuracy of the antenna phase center measurement and adjustment is improved by more than 10 times, and the measurement method is simple, the adjustment method is highly reliable and easy to implement.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for precise measurement, calculation and adjustment of the phase center of an SKA antenna is implemented based on a photogrammetry system, 16 feed fixtures and a Stewart mechanism. The photogrammetry system measures the main surface of the SKA antenna and the 16 feed fixtures through a digital industrial photogrammetry system; the 16 feed fixtures are evenly distributed in the circumferential direction of the SKA antenna feed, one end of which is inserted into a reserved light hole of the SKA antenna feed, and a photogrammetry mark is pasted on the upper surface of the other end; the fixed plane of the Stewart mechanism is connected to the SKA antenna ARM, and the moving plane of the Stewart mechanism is connected to the feed of the SKA antenna. Specifically, the method comprises the following steps:

[0007] Step 1: Measure the photogrammetric marks of the main surface of the SKA antenna and 16 feed fixtures using the photogrammetric system, and construct the main surface coordinate system of the SKA antenna O 0 -X 0 Y 0 Z 0; Set the SKA antenna phase centroid error threshold;

[0008] Step 2: According to the SKA antenna main surface coordinate system O 0 -X 0 Y 0 Z 0 ; Calculate the theoretical coordinate system of SKA antenna feed The SKA antenna phase-centre theoretical coordinate system

[0009] Step 3: Obtain the coordinates of 16 feed fixture points based on the photogrammetry system, and then calculate the actual coordinate system of the SKA antenna feed. According to the actual coordinate system of the SKA antenna feed Calculate the actual coordinate system of the SKA antenna phase center

[0010] If the actual coordinate system of the SKA antenna phase center The SKA antenna phase-centre theoretical coordinate system If the difference is less than the SKA antenna phase center error threshold, the SKA antenna phase center precision measurement calculation adjustment is completed, otherwise, go to step 4;

[0011] Step 4: According to the actual coordinate system of the SKA antenna feed The SKA antenna feed theoretical coordinate system The Stewart mechanism is used to adjust the position of the SKA antenna feed, and the process returns to step 3.

[0012] Furthermore, the 16 feed fixtures have the same shape and size, all of which are in the form of stepped shafts. The lower section of the feed fixture is a cylindrical shaft with a diameter of 6 mm and a height of 10 mm, which is used to be inserted into the 6 mm diameter light holes evenly distributed in the circumferential direction of the SKA antenna feed source. The middle section of the feed fixture is a cylindrical shaft with a diameter of 14 mm and a height of 2 mm, which is used to position the fixture angle. The upper section of the feed fixture is a cylindrical shaft with a diameter of 10 mm and a height of 3 mm, and a photogrammetry mark with a diameter of 10 mm is pasted on its upper surface, which is used to reflect light, i.e., the measurement of the photogrammetry system; the axes of the cylindrical shafts of the lower, middle and upper sections of the feed fixture coincide.

[0013] Furthermore, the specific method of step 2 is:

[0014] Step 201: According to the SKA antenna main surface coordinate system O 0 -X 0 Y 0 Z 0 , calculate the theoretical coordinate system of SKA antenna feed The translation transformation matrix and rotation transformation matrix:

[0015]

[0016] in, and They represent the SKA antenna main surface coordinate system O 0 -X 0 Y 0 Z 0 The position coordinates and angular orientation of

[0017] and They represent the theoretical coordinate system of SKA antenna feed respectively. The position coordinates and angular orientation of

[0018] T x 、T y 、T z They are the SKA antenna principal surface coordinate system O 0 -X 0 Y 0 Z 0 The SKA antenna feed theoretical coordinate system The translation transformation value on the xyz axis;

[0019] α 1 , α 2 , α 3 They are the SKA antenna principal surface coordinate system O 0 -X 0 Y 0 Z 0 The SKA antenna feed theoretical coordinate system The rotation transformation value around the xyz axis;

[0020] Step 202: According to the SKA antenna feed theoretical coordinate system Calculate the theoretical coordinate system of the SKA antenna phase center The translation transformation matrix and rotation transformation matrix:

[0021]

[0022]

[0023] in, and They represent the SKA antenna phase-centre theoretical coordinate system respectively. The position coordinates and angular orientation of

[0024] R x , R y , R z They are the theoretical coordinate systems of SKA antenna feed The SKA antenna phase-centre theoretical coordinate system The translation transformation value on the xyz axis;

[0025] β 1 , β 2 , β 3 They are the theoretical coordinate systems of SKA antenna feed The SKA antenna phase-centre theoretical coordinate system The rotation transform value around the xyz axis.

[0026] Furthermore, in step 3, the coordinates of 16 feed fixture points are obtained according to the photogrammetry system, and then the actual coordinate system of the SKA antenna feed is calculated. The specific method is:

[0027] The photogrammetry system measures the photogrammetry marks on the 16 feed fixtures, calculates the coordinates of the 16 feed fixture points in the measurement coordinate system, and then converts the common point of the reference point to obtain the SKA antenna main surface coordinate system O 0 -X 0 Y 0 Z 0 The coordinates of the 16 feed fixture points under the 16-axis coordinate system are fitted to construct plane A, and plane A is defined as the actual coordinate system of the SKA antenna feed. Plane, fit the coordinates of 16 feed fixture points to construct circle B and obtain its center O, and define the center O as the coordinate origin of the actual coordinate system of the feed The feed fixture point on the neutral plane of the SKA antenna and the coordinate origin A connection is defined as Axis, according to the right-hand rule, from the origin of the coordinate Plane and The three axis elements establish the actual coordinate system of the SKA antenna feed

[0028] Due to the adoption of the above technical solution, the beneficial effects of the present invention compared with the prior art are:

[0029] 1. The present invention adopts a photogrammetry system to measure the antenna feed, and utilizes the high precision, non-contact and high efficiency characteristics of the photogrammetry system to accurately measure and calculate the position and posture of the SKA antenna feed, providing a guarantee for the calculation and adjustment of the SKA antenna phase center measurement.

[0030] 2. The present invention adopts a feed tooling and utilizes the good designability and manufacturability of metal materials to design the feed tooling. It can not only rely on the precise manufacturing of the tooling and be installed on the circular light hole of the antenna feed, but also meet the requirements of the photogrammetry system for reflective marks.

[0031] 3. The present invention adopts Stewart mechanism adjustment, which has the advantages of high adjustment accuracy, quantifiable and sustainable adjustment. It can realize the precise adjustment of antenna feed to the greatest extent, and provides an important guarantee for realizing efficient and precise adjustment of SKA antenna feed.

[0032] 4. The present invention adopts a combination of feed tooling and Stewart mechanism, the measurement method is simple and the technology is mature, and it is particularly suitable for the measurement of high-precision feed posture of antennas.

[0033] 5. The present invention uses the antenna feed to reversely calculate the phase center, and uses the spatial relative position relationship between the feed and the phase center to accurately measure the antenna phase center position under the current feed position, providing a guarantee for the accurate calculation of the SKA antenna phase center position. The antenna phase center measurement and adjustment efficiency is improved by 5 times, and the antenna phase center position accuracy is improved by more than 10 times. The antenna phase center measurement, calculation and adjustment method is simple, efficient and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the relative positions of the coordinate systems of the main surface of the SKA antenna, the antenna feed and the center of the phase in an embodiment of the present invention.

[0035] Figure 2 Schematic diagram of a top view of the SKA antenna feed according to an embodiment of the present invention.

[0036] Figure 3 It is a front view schematic diagram of the SKA antenna feed tooling in an embodiment of the present invention.

[0037] Figure 4 Schematic diagram of photogrammetry mark in an embodiment of the present invention.

[0038] Figure 5 Schematic diagram of the Stewart mechanism in an embodiment of the present invention.

[0039] Figure 6 for Figure 5 Schematic diagram of the telescopic rod. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0041] A method for precise measurement, calculation and adjustment of the phase center of an SKA antenna is implemented based on a photogrammetry system, 16 feed fixtures and a Stewart mechanism. The photogrammetry system measures the main surface of the SKA antenna and the 16 feed fixtures through a digital industrial photogrammetry system; Figure 2As shown, the 16 feed fixtures are evenly distributed in the circumferential direction of the SKA antenna feed, one end is inserted into the reserved light hole of the SKA antenna feed, and the photogrammetry mark is pasted on the upper surface of the other end; the fixed plane of the Stewart mechanism is connected to the SKA antenna ARM, and the moving plane of the Stewart mechanism is connected to the feed of the SKA antenna. Specifically, the following steps are included:

[0042] Step 1: Measure the photogrammetric marks of the main surface of the SKA antenna and 16 feed fixtures using the photogrammetric system, and construct the main surface coordinate system of the SKA antenna O 0 -X 0 Y 0 Z 0 ; Set the SKA antenna phase centroid error threshold;

[0043] Step 2, such as Figure 1 As shown, according to the SKA antenna main surface coordinate system O 0 -X 0 Y 0 Z 0 ; Calculate the theoretical coordinate system of SKA antenna feed The SKA antenna phase-centre theoretical coordinate system

[0044] Step 3: Obtain the coordinates of 16 feed fixture points based on the photogrammetry system, and then calculate the actual coordinate system of the SKA antenna feed. According to the actual coordinate system of the SKA antenna feed Calculate the actual coordinate system of the SKA antenna phase center

[0045] If the actual coordinate system of the SKA antenna phase center The SKA antenna phase-centre theoretical coordinate system If the difference is less than the SKA antenna phase center error threshold, the SKA antenna phase center precision measurement calculation adjustment is completed, otherwise, go to step 4;

[0046] Step 4: According to the actual coordinate system of the SKA antenna feed The SKA antenna feed theoretical coordinate system The Stewart mechanism is used to adjust the position of the SKA antenna feed, and the process returns to step 3.

[0047] Specifically, in this embodiment, Figure 5 As shown, the Stewart mechanism includes a moving platform, a hinge, a telescopic rod, a reducer, and a ball node, which together constitute the basic structure of the device; Figure 6This is a schematic diagram of the telescopic rod of the Stewart mechanism, including the upper hinge, telescopic rod, lower hinge, and reducer, which is an important carrier for realizing the precise adjustment of the Stewart mechanism. The telescopic rod adopts a worm gear transmission, with a reduction ratio of 1:20, a trapezoidal screw, and a screw lead of 6mm. The hand wheel rotates one circle to extend or shorten the length by 0.3mm, which plays a role in precise adjustment;

[0048] Furthermore, if Figure 3 As shown, the 16 feed fixtures have the same shape and size, all of which are in the form of stepped shafts. The lower section of the feed fixture is a cylindrical shaft with a diameter of 6 mm and a height of 10 mm, which is used to insert into the 6 mm diameter light holes evenly distributed in the circumferential direction of the SKA antenna feed source. The middle section of the feed fixture is a cylindrical shaft with a diameter of 14 mm and a height of 2 mm, which is used to locate the fixture angle. The upper section of the feed fixture is a cylindrical shaft with a diameter of 10 mm and a height of 3 mm. Figure 4 As shown, a photogrammetry mark with a diameter of 10 mm is pasted on its upper surface for reflecting light, i.e., the measurement of the photogrammetry system; the cylindrical axis of the lower, middle and upper sections of the feed tooling coincide.

[0049] Specifically, in this embodiment, the feed tooling uses 1Cr18Ni9Ti as raw material;

[0050] Furthermore, the specific method of step 2 is:

[0051] Step 201: According to the SKA antenna main surface coordinate system O 0 -X 0 Y 0 Z 0 , calculate the theoretical coordinate system of SKA antenna feed The translation transformation matrix and rotation transformation matrix:

[0052]

[0053] in, and They represent the SKA antenna main surface coordinate system O 0 -X 0 Y 0 Z 0 The position coordinates and angular orientation of

[0054] and They represent the theoretical coordinate system of SKA antenna feed respectively. The position coordinates and angular orientation of

[0055] A coordinate system can be characterized by its position coordinates and angular orientation;

[0056] Step 202: According to the SKA antenna feed theoretical coordinate system Calculate the theoretical coordinate system of the SKA antenna phase center The translation transformation matrix and rotation transformation matrix:

[0057]

[0058] in, and They represent the SKA antenna phase-centre theoretical coordinate system respectively. The position coordinates and angle orientation.

[0059] Furthermore, in step 3, the coordinates of 16 feed fixture points are obtained according to the photogrammetry system, and then the actual coordinate system of the SKA antenna feed is calculated. The specific method is:

[0060] The photogrammetry system measures the photogrammetry marks on the 16 feed fixtures, calculates the coordinates of the 16 feed fixture points in the measurement coordinate system, and then converts the common point of the reference point to obtain the SKA antenna main surface coordinate system O 0 -X 0 Y 0 Z 0 The coordinates of the 16 feed fixture points under the 16-axis coordinate system are fitted to construct plane A, and plane A is defined as the actual coordinate system of the SKA antenna feed. Plane, fit the coordinates of 16 feed fixture points to construct circle B and obtain its center O, and define the center O as the coordinate origin of the actual coordinate system of the feed The feed fixture point on the neutral plane of the SKA antenna and the coordinate origin A connection is defined as Axis, according to the right-hand rule, from the origin of the coordinate Plane and The three axis elements establish the actual coordinate system of the SKA antenna feed

[0061] Afterwards, according to the actual coordinate system of the SKA antenna feed Calculate the actual coordinate system of the SKA antenna phase center Specifically, according to the actual coordinate system of the SKA antenna feed Calculate the actual coordinate system of the SKA antenna phase center The translation transformation matrix and rotation transformation matrix:

[0062]

[0063] in, and Represents the actual coordinate system of the SKA antenna phase center The position coordinates and angle orientation.

[0064] In summary, compared with the existing literature, the method for precise measurement, calculation and adjustment of the SKA antenna phase center adopted in the present invention is novel in measurement, calculation and adjustment, and cleverly combines the advantages of the high-precision measurement method of the digital photogrammetry system and the precise adjustment of the Stewart mechanism, making it easy to achieve high-precision measurement and adjustment of the SKA antenna phase center, greatly improving the measurement efficiency of the SKA antenna phase center, and further the measurement accuracy and adjustment accuracy are very high. Moreover, the feed tooling is easy to process and manufacture, with low manufacturing cost, and is suitable for high-precision measurement and adjustment of the SKA antenna phase center.

[0065] The invention discloses a method for precisely measuring, calculating and adjusting the phase center of an SKA antenna. A feed fixture with a photogrammetry mark affixed thereto is installed on the antenna feed by combining a digital photogrammetry system with a Stewart mechanism. Six telescopic rods of the Stewart mechanism are adjusted to an initial rod length. The main surface and the feed are measured by a photogrammetry system to calculate the feed posture. The antenna phase center posture is then inversely calculated. Finally, the six telescopic rods of the Stewart mechanism are used to adjust the rod length change to achieve the purpose of precise adjustment. The antenna phase center posture measurement, calculation and adjustment method is suitable for the phase center posture measurement and adjustment of SKA antennas and other high-precision reflector antennas. After the antenna phase center measurement, calculation and adjustment method is adopted, the antenna phase center measurement and adjustment efficiency is increased by 5 times, and the antenna phase center posture accuracy is increased by more than 10 times. The antenna phase center measurement, calculation and adjustment method is simple, efficient and easy to implement. The feed fixture design and manufacturing method is simple, low-cost and easy to implement.

[0066] Those skilled in the art will appreciate that the embodiments described are intended to help readers understand the principles of the present invention, and should be understood that the scope of protection of the present invention is not limited to the embodiments described. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for precise measurement, calculation and adjustment of SKA antenna phase centroid, characterized in that: It is implemented based on a photogrammetry system, 16 feed fixtures and a Stewart mechanism. The photogrammetry system measures the main surface of the SKA antenna and 16 feed fixtures through a digital industrial photogrammetry system. The 16 feed fixtures are evenly distributed in the circumferential direction of the SKA antenna feed, one end of which is inserted into the reserved light hole of the SKA antenna feed, and a photogrammetry mark is pasted on the upper surface of the other end. The fixed plane of the Stewart mechanism is connected to the SKA antenna ARM, and the moving plane of the Stewart mechanism is connected to the feed of the SKA antenna. Specifically, the following steps are included: Step 1: Measure the photogrammetric marks of the main surface of the SKA antenna and 16 feed fixtures according to the photogrammetric system, and construct the main surface coordinate system O0-X0Y0Z0 of the SKA antenna; set the SKA antenna phase center error threshold; Step 2: Calculate the theoretical coordinate system of the SKA antenna feed according to the SKA antenna main surface coordinate system O0-X0Y0Z0 The SKA antenna phase-centre theoretical coordinate system Step 3: Obtain the coordinates of 16 feed fixture points based on the photogrammetry system, and then calculate the actual coordinate system of the SKA antenna feed. According to the actual coordinate system of the SKA antenna feed Calculate the actual coordinate system of the SKA antenna phase center If the actual coordinate system of the SKA antenna phase center The SKA antenna phase-centre theoretical coordinate system If the difference is less than the SKA antenna phase center error threshold, the SKA antenna phase center precision measurement calculation adjustment is completed, otherwise, go to step 4; Step 4: According to the actual coordinate system of the SKA antenna feed The SKA antenna feed theoretical coordinate system The Stewart mechanism is used to adjust the position of the SKA antenna feed, and the process returns to step 3.

2. The method for precise measurement, calculation and adjustment of SKA antenna phase centroid according to claim 1, characterized in that: The 16 feed fixtures have the same shape and size, all of which are in the form of stepped shafts. The lower section of the feed fixture is a cylindrical shaft with a diameter of 6 mm and a height of 10 mm, which is used to be inserted into the 6 mm diameter light holes evenly distributed in the circumferential direction of the SKA antenna feed. The middle section of the feed fixture is a cylindrical shaft with a diameter of 14 mm and a height of 2 mm, which is used to position the fixture angle. The upper section of the feed fixture is a cylindrical shaft with a diameter of 10 mm and a height of 3 mm, and a photogrammetry mark with a diameter of 10 mm is pasted on its upper surface, which is used to reflect light, i.e., the measurement of the photogrammetry system; the axes of the cylindrical shafts of the lower, middle and upper sections of the feed fixture coincide.

3. The method for precise measurement, calculation and adjustment of SKA antenna phase center according to claim 1, characterized in that: The specific method of step 2 is: Step 201, calculate the SKA antenna feed theoretical coordinate system according to the SKA antenna main surface coordinate system O0-X0Y0Z0 The translation transformation matrix and rotation transformation matrix: in, and They respectively represent the position coordinates and angular orientation of the SKA antenna main surface coordinate system O0-X0Y0Z0; and They represent the theoretical coordinate system of SKA antenna feed respectively. The position coordinates and angular orientation of T x , T y , T z They are respectively the SKA antenna main surface coordinate system O0-X0Y0Z0 and the SKA antenna feed theoretical coordinate system The translation transformation value on the xyz axis; α1, α2, and α3 are the SKA antenna main surface coordinate system O0-X0Y0Z0 and the SKA antenna feed theoretical coordinate system respectively The rotation transformation value around the xyz axis; Step 202: According to the SKA antenna feed theoretical coordinate system Calculate the theoretical coordinate system of the SKA antenna phase center The translation transformation matrix and rotation transformation matrix: in, and They represent the SKA antenna phase-centre theoretical coordinate system respectively. The position coordinates and angular orientation of R x , R y , R z They are the theoretical coordinate systems of SKA antenna feed The SKA antenna phase-centre theoretical coordinate system The translation transformation value on the xyz axis; β1, β2, and β3 are the theoretical coordinate systems of the SKA antenna feed. The SKA antenna phase-centre theoretical coordinate system The rotation transform value around the xyz axis.

4. The method for precise measurement, calculation and adjustment of SKA antenna phase center according to claim 3, characterized in that: In step 3, the coordinates of 16 feed fixture points are obtained according to the photogrammetry system, and then the actual coordinate system of the SKA antenna feed is calculated. The specific method is: The photogrammetry system measures the photogrammetry marks on the 16 feed fixtures, calculates the coordinates of the 16 feed fixture points in the measurement coordinate system, and then converts the common point of the reference point to obtain the coordinates of the 16 feed fixture points in the SKA antenna main surface coordinate system O0-X0Y0Z0. The 16 feed fixture point coordinates are fitted to construct plane A, and plane A is defined as the actual coordinate system of the SKA antenna feed. Plane, fit the coordinates of 16 feed fixture points to construct circle B and obtain its center O, and define the center O as the coordinate origin of the actual coordinate system of the feed The feed fixture point on the neutral plane of the SKA antenna and the coordinate origin The connection is defined as Axis, according to the right-hand rule, from the origin of the coordinate Plane and The three axis elements establish the actual coordinate system of the SKA antenna feed

Images