CN104089594B - SAR days line automation accurate measurement methods of satellite large scale planar array - Google Patents

Abstract

The invention discloses an automatic precision measurement method for SAR antennas. The target points of the antenna front are measured by a laser radar measurement system, and the flatness of the front and the direction of the plane normal are calculated by least square fitting; the satellite is measured by the theodolite measurement system. The reference mirror and the public target ball point to establish the relationship between the public target ball point and the satellite mechanical coordinate system; then use the lidar to measure the public target ball point to establish the relationship between the satellite mechanical coordinate system and the laser radar measurement coordinate system, and finally Obtain the direction of the normal line of the antenna array in the satellite coordinate system; in the multiple deployment tests of the antenna, use the radar single-point automatic measurement function to automatically complete the plane measurement after deployment, and evaluate the repeatability of the deployment flatness and pointing. The invention can complete the high-precision and automatic measurement of the flatness and pointing precision of the antenna, meet the precision requirements of 0.2mm for the plane point coordinate within 30m and 20" for the angle measurement precision, and greatly improve the measurement efficiency.

Description

Automatic precision measurement method for satellite large-scale planar array SAR antenna

technical field

The invention belongs to the technical field of industrial measurement, and in particular relates to an automatic precision measurement method for a satellite large-scale planar array SAR antenna.

Background technique

With the increasing demand for satellite antennas, the size of antennas is getting larger and larger, and the requirements for profile and installation accuracy are also getting higher and higher. The precision measurement of SAR antenna is a key link in the quality control of the development of the satellite, and its installation accuracy and SAR antenna deployment configuration directly affect the quality of the satellite's in-orbit imaging. The SAR antenna can be composed of multiple antenna panels. During the assembly process, it is necessary to measure the overall flatness of the antenna after it is installed on the satellite and the pointing accuracy of the array in the satellite mechanical coordinate system. The measurement accuracy of the plane point coordinates is required to be 0.2mm. The measurement accuracy requires 20″.

In recent years, antenna precision measurement technology has developed rapidly, and has developed from traditional mechanical, optical and electrical measurement methods to mature commercial high-precision industrial measurement systems. According to different precise measurement items and the characteristics of the antenna under test, different measurement systems are used and specific measurement methods are designed. At present, the instruments and equipment used in antenna precision measurement at home and abroad mainly include: theodolite measurement system, photogrammetry system, three-coordinate measurement system, laser tracking measurement system, laser radar scanning measurement system, etc.

At present, in the precise measurement process of domestic spacecraft assembly, the satellite mechanical coordinate system and the satellite instrument equipment coordinate system are represented by the coordinate system of the installed cubic mirror. Use the theodolite measurement system to realize the measurement of the mirror normal and the mirror center coordinate point. The mirror normal measurement principle is the autocollimation measurement principle, and the point coordinate measurement principle is the forward intersection measurement principle.

When the theodolite measurement system is measuring a point, two theodolites are required for calibration and measurement, and two people are required to manually aim at the point. The measurement accuracy is low and the speed is slow. During the deployment of the antenna, multiple measurements are required, which is time-consuming and manpower-intensive. The laser radar measurement system has a measurement range of up to 30m. It performs three-dimensional scanning measurement of the target and establishes a mathematical three-dimensional model of the target. The scanning speed can reach 1000 points/second, and the highest scanning accuracy can reach 0.1mm. Through the joint precision measurement method of the laser radar measurement system and theodolite measurement system, the high-precision and automatic measurement of the antenna can be realized.

Contents of the invention

The purpose of the present invention is to provide a new automatic precision measurement method for satellite large-scale planar array SAR antennas, to realize the overall flatness of the antenna array, the measurement of the array pointing accuracy under the star mechanical coordinate system, and the automatic repeated measurement of multiple deployment tests , designed to improve the measurement range, measurement accuracy and degree of automation.

To achieve the above object, the present invention adopts the following technical solutions:

A kind of satellite large-scale planar array SAR antenna automatic fine measurement method, comprises the following steps:

(1) Before the antenna is installed on the satellite, the return light reflection mark points are evenly pasted on the measured array surface of the antenna, and the number of points is large enough to reflect the overall flatness of the antenna;

(2) After the antenna is installed on the satellite, paste no less than 4 target ball bases near the antenna unfolding measurement station to avoid the bases being located on the same straight line or on the same plane; one of the target ball bases is a public target ball A base, each target ball base is provided with a target ball;

(3) After the antenna is deployed, set up the laser radar measurement system at a suitable position directly in front of the center of the antenna array, so that all the marking points on the array can be within the measurement range of the radar, and the position of the laser radar is fixed during the measurement process;

(4) Use the single-point manual measurement function of the laser radar to measure the marker points pasted on the antenna array in the laser radar system coordinate system, and calculate the array flatness and the direction of the plane normal through least squares fitting;

(5) Set up three theodolites, measure the cube mirror representing the satellite mechanical coordinate system on the satellite, and measure the target ball on the base of the public target ball to obtain the three-dimensional point of the center point of the public target ball in the satellite mechanical coordinate system coordinate;

(6) Use the target ball measurement function of the laser radar to measure the target ball on the public target ball base, and obtain the three-dimensional point coordinates of the public target ball center point in the laser radar coordinate system;

(7) Establish the conversion relationship between the laser radar coordinate system and the satellite coordinate system through the conversion of the common target ball point, so as to obtain the normal line of the antenna array in the satellite coordinate system;

(8) In multiple deployment tests, the multi-point automatic measurement function of the laser radar is used to measure the marker points pasted on the antenna array, and the array flatness and the direction of the plane normal are calculated by least squares fitting.

Wherein, the number of reflective marker points is more than 120, preferably more than 150, more preferably 180-200.

Among them, the antenna array to be tested (antenna array) is an array composed of four SAR antenna single boards symmetrically arranged on both sides of the satellite in sequence and unfolded.

The invention solves the technical problem of high precision and automatic measurement of the large-scale planar array SAR antenna, and has the following effects:

It breaks through the traditional limitation of using theodolite to measure target points, and uses laser radar to measure antenna array mark points, which improves the accuracy and efficiency of point measurement and reduces the labor intensity of operators. Through the joint measurement of the laser radar and theodolite, the normal angle of the antenna array in the satellite mechanical coordinate system is obtained, which improves the angle measurement accuracy. In several tests, the multi-point automatic measurement function of lidar was used to realize automatic and rapid measurement.

The measuring method of the present invention can meet the precision requirements of 0.2 mm for antenna array point coordinates and 20" of angle measuring precision within a measuring range of 30 m.

Description of drawings

Fig. 1 is a schematic diagram of the position of the SAR antenna array pasted with return light reflection markers in the precise measurement method of the present invention.

Fig. 2 is a schematic diagram of a single retroreflective marker point in the precise measuring method of the present invention.

Figure 3 is a schematic diagram of the layout of the large-scale planar array SAR antenna automatic precision measurement method, in which, 1 is the satellite, 2 is the SAR antenna array composed of four antenna panels, 3 is the electronic theodolite, 4 is the laser radar, 5 is the base and Target ball, 6 is cube mirror.

detailed description

The measurement process of the present invention will be described in detail below in conjunction with the accompanying drawings. These descriptions are only illustrative and are not intended to limit the protection scope of the present invention.

Figure 1 is a schematic diagram of pasting the return light reflection mark points on the SAR antenna front. In the figure, the black dots represent the mark points. On the single antenna face 2 panel, 192 mark points are evenly pasted. The actual reflective marker points are shown in Figure 2. The outer part is a black area, and the inner circle is a white reflective area. The internal reflection brightness is hundreds of times higher than that of the outer part, so that the radar can extract the circular boundary and obtain the center of the marker point.

Figure 3 is a schematic diagram of the layout of the automatic precision measurement method for large-scale planar array SAR antennas. The satellite is placed horizontally, and four SAR antenna boards (2-1, 2-2, 2-3, 2-4) are installed on satellite 1. and fully unfolded in turn. Arrange 5 target balls and base 5 on the ground around the star, and stick the base on the ground with hot melt glue. Set up three theodolites and a laser radar measurement system directly in front of the antenna array.

Theodolite 3-1 and theodolite 3-2 are collimated with two adjacent faces of cube mirror 6 respectively, measure mirror surface normal direction, theodolite 3-3 and theodolite 3-1 calibration, measure cube mirror central point coordinates, cube mirror The relationship with the satellite mechanical coordinate system has been established before, so at this time, the satellite mechanical coordinate system is obtained through the coordinate system of the cube mirror. Then use the theodolite 3-1 and 3-3 to measure the center point of the target ball on the public target ball base, and obtain the three-dimensional point coordinate value of the public target ball center point in the satellite mechanical coordinate system.

Use the single-point manual measurement function of Lidar 4 to measure the marker points pasted on the antenna array in the Lidar system coordinate system, and obtain their three-dimensional point coordinates in the Lidar coordinate system. Fit the measurement points through least squares to calculate the least squares fitting plane, find the maximum and minimum distances from the plane, the difference between the two is the front flatness, and the normal of the fitting plane is Front normal. Use the target ball measurement function of the laser radar 4 to measure the target ball on the public target ball base, and obtain the three-dimensional point coordinates of the public target ball center point in the laser radar coordinate system. Through the conversion of the common target ball point, the conversion relationship between the lidar coordinate system and the satellite coordinate system is established, so as to obtain the normal direction of the antenna front 2 in the satellite coordinate system.

In many tests, because the relationship between the points on each antenna panel remains basically unchanged, only the overall displacement of each antenna panel, so the multi-point automatic measurement function of the laser radar is used to measure the points pasted on the antenna array. Mark points to improve measurement efficiency. In each unfolding test, manually measure 4 or more marker points that are not on the same straight line on each antenna panel, and then select the corresponding points of the initial measurement, and then use the multi-point automatic measurement function of LiDAR 4, Automatically calculate the theoretical position of the measured point and perform automatic measurement. The measurement methods of the four antenna panels are consistent. This method can be used to measure all the marker points for each test, and the data processing method after measuring the points is the same as before.

Although the specific embodiments of the present invention have been described and illustrated in detail above, it should be pointed out that we can make various changes and modifications to the above embodiments, but these do not depart from the spirit of the present invention and the appended rights. Request the range described.

Claims (4)

1. a kind of automation accurate measurement method of satellite large scale planar array SAR antennas, comprises the following steps：

(1) antenna is installed to before satellite, and uniform stickup retro-reflective target point on front is tested in antenna, and the quantity of point is enough It is many to reflect antenna integral planar degree；

(2) antenna is installed to after satellite, deploys to paste the target ball pedestal that quantity is no less than 4 near measurement station in antenna, Pedestal is avoided to be located on same straight line or same plane；One of target ball pedestal is public target ball pedestal, each target ball base Target ball is both provided with seat；

(3) after antenna expansion, the correct position immediately ahead of antenna array center sets up lidar measurement system, makes all battle arrays Index point on face can be in the measurement range of radar, and laser radar position is fixed in measurement process；

(4) using the single point manual measurement function of laser radar, under laser radar system coordinate system, glued on measurement antenna array The index point of patch, and pass through least square fitting calculating front flatness and the direction of plane normal；

(5) 3 theodolites are set up, the prism square that subhost tool coordinate system is characterized on satellite is measured, and to public target ball Target ball on pedestal is measured, and obtains three-dimensional point coordinate of the public target ball central point in the mechanical coordinate system of satellite；

(6) measure function to measure the target ball on public target ball pedestal using the target ball of laser radar, obtain public target ball center Three-dimensional point coordinate of the point in laser radar coordinate system；

(7) changed by public target ball point, set up the transformational relation of laser radar coordinate system and co-ordinates of satellite system, defended so as to obtain Antenna array normal under star coordinate system；

(8) in multiple expansion experiment, using the multiple spot automatic measurement function of laser radar, the mark pasted on measurement antenna array Will point, the direction of front flatness and plane normal is calculated by least square fitting, and it is 4 pieces that wherein antenna, which is tested front, The front that SAR antennas veneer is symmetrically successively set on satellite both sides and constituted after deploying.

2. accurate measurement method is automated as claimed in claim 1, wherein, the quantity of reflective marker point is more than 120.

3. accurate measurement method is automated as claimed in claim 2, wherein, the quantity of reflective marker point is more than 150.

4. accurate measurement method is automated as claimed in claim 3, wherein, the quantity of reflective marker point is 180-200.