SKA antenna phase center precise measurement calculation adjustment method

Abstract

The application discloses a kind of SKA antenna phase heart precision measurement calculation adjustment methods, it is related to antenna measurement technical field.The application is realized based on photogrammetry system, 16 feed toolings and Stewart mechanism, first, the theoretical coordinate system of SKA antenna feed and SKA antenna phase heart is calculated, and according to the measurement of 16 feed toolings to photogrammetry system, the actual coordinate system of SKA antenna feed and SKA antenna phase heart is obtained, then according to the difference between theoretical coordinate system and actual coordinate system, adjustment is carried out using Stewart mechanism, until SKA antenna phase heart is adjusted accurately.After using the antenna phase heart measurement calculation adjustment method, the antenna phase heart measurement adjustment efficiency is improved by 5 times, and the antenna phase heart position and posture accuracy is improved by more than 10 times.The antenna phase heart measurement calculation adjustment method is simple, efficient and easy to implement.

Description

Technical Field

[0001] This invention relates to the field of antenna measurement technology, and in particular to a method for precise measurement, calculation and adjustment of the phase center of an SKA antenna. Background Technology

[0002] The phase center of an antenna is the point at which the equiphase surface of the electromagnetic waves radiated by the antenna approximates a sphere after traveling a certain distance from the antenna. In high-efficiency antenna design, it is generally required that the antenna phase center be accurately measured and precisely adjusted to meet the antenna performance design requirements. During antenna manufacturing and installation, phase center position deviations are unavoidable. As antenna performance requirements become increasingly stringent, the need for precise measurement and adjustment of the antenna phase center is becoming more urgent. Therefore, designing a high-precision measurement, calculation, and adjustment method for antenna phase center position is of practical significance.

[0003] Currently, the main method for measuring and adjusting the antenna phase center is to use the antenna feed sleeve structure for reverse calculation and adjust the angle using shims. This method not only has low measurement accuracy and large calculation errors, but also results in inaccurate adjustment and low efficiency. 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 an SKA antenna. This method is applicable to the precise measurement, calculation and adjustment of the phase center of dual-bias antennas, especially SKA antennas. After adopting this method, the accuracy of antenna phase center measurement and adjustment is improved by more than 10 times. Moreover, the measurement method is simple, the adjustment method is highly reliable and easy to implement.

[0005] To achieve the above objectives, 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 disclosed, 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 using a digital industrial photogrammetry system. The 16 feed fixtures are evenly distributed around the circumference of the SKA antenna feed, with one end inserted into a pre-drilled aperture in the feed and a photogrammetry mark affixed to 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 is connected to the feed of the SKA antenna. Specifically, the method includes the following steps:

[0007] Step 1: Measure the photogrammetric marks of the SKA antenna main surface and 16 feed fixtures using the photogrammetric system, and construct the SKA antenna main surface coordinate system O0-X0Y0Z0; set the SKA antenna phase center error threshold.

[0008] Step 2: Calculate the theoretical coordinate system of the SKA antenna feed based on the principal plane coordinate system O0-X0Y0Z0. With respect to the SKA antenna's coaxial theoretical coordinate system

[0009] Step 3: Obtain the coordinates of the 16 feed tooling points using the photogrammetry system, and then calculate the actual coordinate system of the SKA antenna feed. And based on 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 is With respect to the SKA antenna's coaxial theoretical coordinate system If the difference is less than the SKA antenna phase center error threshold, then the precise measurement, calculation and adjustment of the SKA antenna phase center is completed; otherwise, proceed to step 4.

[0011] Step 4, based on the actual coordinate system of the SKA antenna feed. With respect to the theoretical coordinate system of the SKA antenna feed The difference is used to adjust the pose of the SKA antenna feed using a Stewart mechanism, and then the process returns to step 3.

[0012] Furthermore, the 16 feed fixtures are identical in shape and size, all being stepped shafts. The lower section of the feed fixture is a cylindrical shaft with a diameter of 6mm and a height of 10mm, used to insert into the 6mm diameter optical holes evenly distributed around the circumference of the SKA antenna feed. The middle section of the feed fixture is a cylindrical shaft with a diameter of 14mm and a height of 2mm, used to position the fixture angle. The upper section of the feed fixture is a cylindrical shaft with a diameter of 10mm and a height of 3mm, with a 10mm diameter photogrammetry mark pasted on its upper surface for reflecting light, i.e., for measurement by 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 as follows:

[0014] Step 201: Calculate the theoretical coordinate system of the SKA antenna feed based on the principal plane coordinate system O0-X0Y0Z0 of the SKA antenna. Translation and rotation transformation matrices:

[0015]

[0016] in, and These represent the position coordinates and angular orientation of the SKA antenna principal plane coordinate system O0-X0Y0Z0, respectively.

[0017] and Representing the theoretical coordinate system of the SKA antenna feed respectively Position coordinates and angle orientation;

[0018] T x T y T z These represent the principal plane coordinate system O0-X0Y0Z0 of the SKA antenna and the theoretical coordinate system of the SKA antenna feed, respectively. Translation values ​​along the x, y, and z axes;

[0019] α1, α2, and α3 represent the principal plane coordinate system O0-X0Y0Z0 of the SKA antenna and the theoretical coordinate system of the SKA antenna feed, respectively. Rotational transformation values ​​about the xyz axes;

[0020] Step 202, according to the SKA antenna feed theoretical coordinate system Calculate the theoretical coordinate system of the SKA antenna coherence Translation and rotation transformation matrices:

[0021]

[0022]

[0023] in, and Representing the SKA antenna's piezocentric theoretical coordinate system Position coordinates and angle orientation;

[0024] R x R y R z These are the theoretical coordinate systems of the SKA antenna feed. With respect to the SKA antenna's coaxial theoretical coordinate system Translation values ​​along the x, y, and z axes;

[0025] β1, β2, and β3 are the theoretical coordinate systems of the SKA antenna feed. With respect to the SKA antenna's coaxial theoretical coordinate system Rotational transformation values ​​about the xyz axes.

[0026] Furthermore, in step 3, the coordinates of the 16 feed tooling points are obtained based on the photogrammetry system, and then the actual coordinate system of the SKA antenna feed is calculated. The specific method is as follows:

[0027] The photogrammetric system measures the photogrammetric marks on 16 feed fixtures. The coordinates of these 16 feed fixture points in the measurement coordinate system are calculated. Then, through a common point transformation, the coordinates of the 16 feed fixture points in the SKA antenna principal plane coordinate system O0-X0Y0Z0 are obtained. Plane A is constructed by fitting these coordinates, and plane A is defined as the actual coordinate system of the SKA antenna feed. In a plane, a circle B is constructed by fitting the coordinates of 16 feed tooling points, and its center O is obtained. The center O is defined as the origin of the actual coordinate system of the feed. The feed fixture point on the neutral plane of the SKA antenna and the origin of the coordinate system The connection is defined as The axis, according to the right-hand rule, is the axis originating from the coordinate origin. plane and Establishing the actual coordinate system of the SKA antenna feed using the three axes

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

[0029] 1. This invention uses a photogrammetry system to measure the antenna feed. By utilizing the high precision, non-contact and high efficiency of the photogrammetry system, the pose of the SKA antenna feed is accurately measured and calculated, providing a guarantee for the measurement, calculation and adjustment of the SKA antenna phase center.

[0030] 2. The present invention adopts a feed fixture, which utilizes the good designability and manufacturability of metal materials to design the feed fixture. It can be precisely manufactured by the fixture and installed on the circumferential aperture of the antenna feed, and can also meet the requirements of the photogrammetry system for the reflection mark.

[0031] 3. The present invention adopts the Stewart mechanism for adjustment, which has the advantages of high adjustment accuracy, quantifiability, and continuous adjustment. It can maximize the precise adjustment of the antenna feed and provide an important guarantee for achieving efficient and precise adjustment of the SKA antenna feed.

[0032] 4. This invention uses a combination of feed fixture and Stewart mechanism, which is simple and technically mature, and is particularly suitable for high-precision measurement of antenna feed position and attitude.

[0033] 5. This invention employs inverse phase center calculation using the antenna feed. By utilizing the spatial relative positional relationship between the feed and the phase center, the antenna phase center pose under the current feed pose can be accurately measured, ensuring accurate calculation of the SKA antenna phase center pose. The efficiency of antenna phase center measurement and adjustment is improved by 5 times, and the accuracy of antenna phase center pose is improved by more than 10 times. This antenna phase center measurement, calculation, and adjustment method is simple, efficient, and easy to implement. Attached Figure Description

[0034] Figure 1 This is a schematic diagram showing the relative positions of the SKA antenna main surface, antenna feed, and phase center in the coordinate system of an embodiment of the present invention.

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

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

[0037] Figure 4 This is a schematic diagram of photogrammetric markers in an embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram of the Stewart mechanism in an embodiment of the present invention.

[0039] Figure 6 for Figure 5 Schematic diagram of the telescopic pole. Detailed Implementation

[0040] The invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0041] A method for precise measurement, calculation, and adjustment of the phase center of an SKA antenna is proposed, 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 using a digital industrial photogrammetry system. Figure 2 As shown, the 16 feed fixtures are evenly distributed around the circumference of the SKA antenna feed. One end is inserted into the pre-reserved optical aperture of the SKA antenna feed, and the upper surface of the other end is affixed with a photogrammetry mark. 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 SKA antenna feed. Specifically, the process includes the following steps:

[0042] Step 1: Measure the photogrammetric marks of the SKA antenna main surface and 16 feed fixtures using the photogrammetric system, and construct the SKA antenna main surface coordinate system O0-X0Y0Z0; set the SKA antenna phase center error threshold.

[0043] Step 2, as follows Figure 1 As shown, based on the principal plane coordinate system O0-X0Y0Z0 of the SKA antenna, the theoretical coordinate system of the SKA antenna feed is calculated. With respect to the SKA antenna's coaxial theoretical coordinate system

[0044] Step 3: Obtain the coordinates of the 16 feed tooling points using the photogrammetry system, and then calculate the actual coordinate system of the SKA antenna feed. And based on 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 is With respect to the SKA antenna's coaxial theoretical coordinate system If the difference is less than the SKA antenna phase center error threshold, then the precise measurement, calculation and adjustment of the SKA antenna phase center is completed; otherwise, proceed to step 4.

[0046] Step 4, based on the actual coordinate system of the SKA antenna feed. With respect to the theoretical coordinate system of the SKA antenna feed The difference is used to adjust the pose of the SKA antenna feed using a Stewart mechanism, and then the process returns to step 3.

[0047] Specifically, in this embodiment, as follows: Figure 5 As shown, the Stewart mechanism includes a moving platform, hinges, telescopic rods, reducers, and ball joints, which together constitute the basic structure of the device. Figure 6 This is a schematic diagram of the Stewart mechanism's telescopic rod, including the upper hinge, telescopic rod, lower hinge, and reducer. It is a crucial component for achieving precise adjustments to the Stewart mechanism. The telescopic rod uses a worm gear drive with a reduction ratio of 1:20, a trapezoidal lead screw, and a lead screw pitch of 6mm. Therefore, one rotation of the handwheel extends or shortens the length by 0.3mm, enabling precise adjustments.

[0048] Furthermore, such as Figure 3 As shown, the 16 feed fixtures are identical in shape and size, all being stepped shafts. The lower section of the feed fixture is a cylindrical shaft with a diameter of 6mm and a height of 10mm, used for insertion into the evenly distributed 6mm diameter optical holes along the circumference of the SKA antenna feed. The middle section of the feed fixture is a cylindrical shaft with a diameter of 14mm and a height of 2mm, used for positioning the fixture angle. The upper section of the feed fixture is a cylindrical shaft with a diameter of 10mm and a height of 3mm. Figure 4 As shown, a 10mm diameter photogrammetric mark is pasted on its upper surface to reflect light, i.e., for the measurement of the photogrammetric system; the cylindrical shaft axes of the lower, middle and upper sections of the feed fixture coincide.

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

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

[0051] Step 201: Calculate the theoretical coordinate system of the SKA antenna feed based on the principal plane coordinate system O0-X0Y0Z0 of the SKA antenna. Translation and rotation transformation matrices:

[0052]

[0053] in, and These represent the position coordinates and angular orientation of the SKA antenna principal plane coordinate system O0-X0Y0Z0, respectively.

[0054] and Representing the theoretical coordinate system of the SKA antenna feed respectively Position coordinates and angle orientation;

[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 coherence Translation and rotation transformation matrices:

[0057]

[0058] in, and Representing the SKA antenna's piezocentric theoretical coordinate system The location coordinates and angle orientation.

[0059] Furthermore, in step 3, the coordinates of the 16 feed tooling points are obtained based on the photogrammetry system, and then the actual coordinate system of the SKA antenna feed is calculated. The specific method is as follows:

[0060] The photogrammetric system measures the photogrammetric marks on 16 feed fixtures. The coordinates of these 16 feed fixture points in the measurement coordinate system are calculated. Then, through a common point transformation, the coordinates of the 16 feed fixture points in the SKA antenna principal plane coordinate system O0-X0Y0Z0 are obtained. Plane A is constructed by fitting these coordinates, and plane A is defined as the actual coordinate system of the SKA antenna feed. In a plane, a circle B is constructed by fitting the coordinates of 16 feed tooling points, and its center O is obtained. The center O is defined as the origin of the actual coordinate system of the feed. The feed fixture point on the neutral plane of the SKA antenna and the origin of the coordinate system The connection is defined as The axis, according to the right-hand rule, is the axis originating from the coordinate origin. plane and Establishing the actual coordinate system of the SKA antenna feed using the three axes

[0061] Then, based on 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 Translation and rotation transformation matrices:

[0062]

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

[0064] In summary, compared with existing literature, the SKA antenna phase center precision measurement, calculation, and adjustment method adopted in this invention is novel. It cleverly combines the advantages of high-precision measurement methods from digital photogrammetry systems and precise adjustment using Stewart mechanisms, making high-precision measurement and adjustment of the SKA antenna phase center easy to achieve, greatly improving the measurement efficiency, and further enhancing both measurement and adjustment accuracy. Moreover, the feed fixture is easy to manufacture and has low production costs, making it suitable for high-precision measurement and adjustment of the SKA antenna phase center.

[0065] This invention discloses a method for precise measurement, calculation, and adjustment of the phase center of an SKA antenna. It employs a combination of a digital photogrammetry system and a Stewart mechanism. A feed fixture with photogrammetry markings is installed on the antenna feed. The six telescopic rods of the Stewart mechanism are then adjusted to their initial lengths. The photogrammetry system measures the master plane and the feed, calculating the feed pose. The antenna phase center pose is then calculated, and finally, the lengths of the six telescopic rods are adjusted to achieve precise adjustment. This method is applicable to the measurement and adjustment of the phase center pose of SKA antennas and other high-precision reflector antennas. Using this method improves the efficiency of antenna phase center measurement and adjustment by 5 times and the accuracy of antenna phase center pose by more than 10 times. The 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 recognize that the described embodiments are intended to help readers understand the principles of the invention and should be understood as not limiting the scope of protection of the invention to the described embodiments. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of the claims of the invention.

Claims

1. A method for precise measurement, calculation, and adjustment of the phase center of an SKA antenna, characterized in that, This system is implemented using 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 using a digital industrial photogrammetry system. The 16 feed fixtures are evenly distributed around the circumference of the SKA antenna feed, with one end inserted into a pre-drilled aperture in the SKA antenna feed and a photogrammetry mark affixed to 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 SKA antenna feed. Specifically, the system includes the following steps: Step 1: Measure the photogrammetric marks of the SKA antenna main surface and 16 feed fixtures using the photogrammetric system, and construct the SKA antenna main surface coordinate system O0-X0Y0Z0; set the SKA antenna phase center error threshold. Step 2: Calculate the theoretical coordinate system of the SKA antenna feed based on the principal plane coordinate system O0-X0Y0Z0. With respect to the SKA antenna's coaxial theoretical coordinate system Step 3: Obtain the coordinates of the 16 feed tooling points using the photogrammetry system, and then calculate the actual coordinate system of the SKA antenna feed. And based on 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 is With respect to the SKA antenna's coaxial theoretical coordinate system If the difference is less than the SKA antenna phase center error threshold, then the precise measurement, calculation and adjustment of the SKA antenna phase center is completed; otherwise, proceed to step 4. Step 4, based on the actual coordinate system of the SKA antenna feed. With respect to the theoretical coordinate system of the SKA antenna feed The difference is used to adjust the pose of the SKA antenna feed using a Stewart mechanism, and then the process returns to step 3.

2. The method for precise measurement, calculation, and adjustment of the phase center of an SKA antenna according to claim 1, characterized in that, The 16 feed fixtures are identical in shape and size, all being stepped shafts. The lower section of the feed fixture is a cylindrical shaft with a diameter of 6mm and a height of 10mm, used to insert into the evenly distributed 6mm diameter optical holes in the circumference of the SKA antenna feed. The middle section of the feed fixture is a cylindrical shaft with a diameter of 14mm and a height of 2mm, used to position the fixture angle. The upper section of the feed fixture is a cylindrical shaft with a diameter of 10mm and a height of 3mm, and a 10mm diameter photogrammetry mark is attached to its upper surface for reflecting light, i.e., for measurement by the photogrammetry system. The axes of the lower, middle, and upper sections of the feed fixture coincide.

3. The method for precise measurement, calculation, and adjustment of the phase center of an SKA antenna according to claim 1, characterized in that, The specific method for step 2 is as follows: Step 201: Calculate the theoretical coordinate system of the SKA antenna feed based on the principal plane coordinate system O0-X0Y0Z0 of the SKA antenna. Translation and rotation transformation matrices: in, and These represent the position coordinates and angular orientation of the SKA antenna principal plane coordinate system O0-X0Y0Z0, respectively. and Representing the theoretical coordinate system of the SKA antenna feed respectively Position coordinates and angle orientation; T x T y T z These represent the principal plane coordinate system O0-X0Y0Z0 of the SKA antenna and the theoretical coordinate system of the SKA antenna feed, respectively. Translation values ​​along the x, y, and z axes; α1, α2, and α3 represent the principal plane coordinate system O0-X0Y0Z0 of the SKA antenna and the theoretical coordinate system of the SKA antenna feed, respectively. Rotational transformation values ​​about the xyz axes; Step 202, according to the SKA antenna feed theoretical coordinate system Calculate the theoretical coordinate system of the SKA antenna coherence Translation and rotation transformation matrices: in, and Representing the SKA antenna's piezocentric theoretical coordinate system Position coordinates and angle orientation; R x R y R z These are the theoretical coordinate systems of the SKA antenna feed. With respect to the SKA antenna's coaxial theoretical coordinate system Translation values ​​along the x, y, and z axes; β1, β2, and β3 are the theoretical coordinate systems of the SKA antenna feed. With respect to the SKA antenna's coaxial theoretical coordinate system Rotational transformation values ​​about the xyz axes.

4. The method for precise measurement, calculation, and adjustment of the phase center of an SKA antenna according to claim 3, characterized in that, In step 3, the coordinates of 16 feed tooling points are obtained based on the photogrammetry system, and then the actual coordinate system of the SKA antenna feed is calculated. The specific method is as follows: The photogrammetric system measures the photogrammetric marks on 16 feed fixtures. The coordinates of these 16 feed fixture points in the measurement coordinate system are calculated. Then, through a common point transformation, the coordinates of the 16 feed fixture points in the SKA antenna principal plane coordinate system O0-X0Y0Z0 are obtained. Plane A is constructed by fitting these coordinates, and plane A is defined as the actual coordinate system of the SKA antenna feed. In a plane, a circle B is constructed by fitting the coordinates of 16 feed tooling points, and its center O is obtained. The center O is defined as the origin of the actual coordinate system of the feed. The feed fixture point on the neutral plane of the SKA antenna and the origin of the coordinate system The connection is defined as The axis, according to the right-hand rule, is the axis originating from the coordinate origin. plane and Establishing the actual coordinate system of the SKA antenna feed using the three axes

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