Method for measuring molded surface of extremely-large on-orbit assembled antenna

Abstract

The invention relates to a method for measuring a molded surface of an extremely-large on-orbit assembled antenna, which comprises the following steps of: installing measuring equipment on a satellite body, carrying out on-orbit calibration, and measuring three-dimensional coordinates of measuring points of an antenna assembly module by using the measuring equipment; selecting two groups of measuring points on the module, calculating space coordinates of the module through a geometrical relationship after measurement, comparing the two groups of coordinates, and when an error is smaller than a precision requirement, taking an average value of the two groups of measuring points as space coordinates of the antenna assembly module relative to the measuring equipment; coordinate transformation is carried out through the installation position information of the measurement equipment on the satellite body, the space coordinates of the antenna assembly module relative to the satellite body are obtained, and the root-mean-square value of the molded surface of the assembly antenna is calculated; and comparing and verifying with a root-mean-square value required by the electrical performance index of the antenna, and ending the measurement when the requirement is met, otherwise, performing profile adjustment according to the measured value and then re-measuring. According to the method, multi-module full-field synchronous measurement in a space environment can be realized, the profile precision of the on-orbit antenna can be accurately predicted, and a foundation is laid for on-orbit adjustment of the assembled antenna.

Description

Technical Field

[0001] This invention relates to a method for measuring the shape of an extremely large on-orbit assembled antenna, belonging to the field of spaceborne deployable antenna technology. Background Technology

[0002] Due to limitations in rocket carrying capacity and space, large deployable space antennas must be foldable and deployable to actively deploy in orbit to form large or giant space structures with dimensions of tens or even hundreds of meters.

[0003] With the rapid development of aerospace technology, single-deployment space antennas are gradually becoming insufficient to meet the demands. On-orbit assembly technology based on modular deployable antenna elements is one of the most effective ways to realize large-size space antennas. To ensure that the antenna meets performance requirements during use, the accuracy of the antenna profile must be measured and monitored, which is also a technical problem that needs to be solved for ultra-large space on-orbit assembled antennas. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a method for measuring the surface accuracy of ultra-large on-orbit assembled antennas, so as to achieve accurate measurement of the surface accuracy of ultra-large on-orbit assembled antennas.

[0005] The technical solution provided by this invention is as follows:

[0006] A method for measuring the profile of an extremely large on-orbit assembled antenna includes the following steps:

[0007] Step 1: Equipment Installation: Install the measuring equipment on the satellite body, and install measuring targets at all measuring points of each antenna assembly module;

[0008] Step 2: Establish satellite coordinate system: Using the satellite as a reference, establish satellite coordinate system C1. Based on the installation location information of the measuring equipment in Step 1, obtain the spatial coordinates of the measuring equipment relative to the satellite coordinate system.

[0009] Step 3: Calibrate the measuring equipment: Using a measuring target, establish a spatial coordinate system C2 for the measuring equipment with the measuring equipment as the origin. The measuring equipment then performs self-calibration based on its built-in algorithm.

[0010] Step 4: Measure the position of the measurement points: All measurements on each antenna assembly module are divided into two groups, each group including at least three measurement points. The target reflection is measured at the measurement points of the antenna assembly module using the measurement equipment on the satellite. The three-dimensional coordinates of the two groups of measurement points in coordinate system C2 are measured, and the three-dimensional coordinates of the two groups of measurement points in coordinate system C1 are obtained through coordinate transformation. The three-dimensional coordinates of the two groups of measurement points in coordinate system C1 are compared. When the error is less than the accuracy requirement, the average value is taken as the measurement point coordinates of the antenna assembly module.

[0011] Step 5: Calculate the boundary position of the antenna assembly module: Based on the coordinates of the measurement points of the antenna assembly module obtained in Step 4, calculate the three-dimensional coordinates of all boundary points of the antenna assembly module in coordinate system C1;

[0012] Step 6: Antenna assembly module surface accuracy calculation: Based on the spatial coordinates of all boundary points of the antenna assembly module and the surface design stress of the antenna assembly module, the internal surface spatial coordinates of the antenna assembly module are inverted to obtain the RMSi value characterizing the surface accuracy of the antenna assembly module, that is, the root mean square value of the i-th antenna assembly module.

[0013] Step 7: Overall antenna profile accuracy calculation: Based on the RMSi value of each antenna assembly module, calculate the RMS value that characterizes the overall profile accuracy of the assembled antenna.

[0014] Step 8: Compare and verify with the antenna electrical performance indicators. The measurement ends when the antenna operation requirements are met. Otherwise, adjust the shape according to the measured value and remeasure. That is, check whether the RMS value meets the requirements. If the requirements are met, check the antenna electrical performance. If the on-orbit service performance is met, the measurement ends. If not, adjust the module spatial position according to the measured value and return to step 3.

[0015] Furthermore, when installing the equipment, the angle between the line connecting the measuring target and the horizontal direction should not be less than 10°.

[0016] Furthermore, the measuring device is a visual measuring device, a microwave measuring device, or a laser measuring device.

[0017] Furthermore, step 4, measuring the location of the measuring point, specifically involves:

[0018] The antenna assembly module is formed by connecting multiple hexagonal module units sequentially. At least one ring of hexagonal module units at the edge of the antenna assembly module's surface is selected as the module under test, and measurement points are set at the vertices of each hexagon. The spatial position of the hexagonal plane can be determined based on the spatial coordinates of three points on a hexagon; therefore, measurement point group a is selected as measurement points 1, 2, and 3, and measurement point group b is selected as measurement points 4, 5, and 6. Based on the geometric position of the hexagonal module units, the spatial coordinates of all six measurement points of the two antenna modules are calculated using the measured values ​​and denoted as A and B.

[0019]

[0020] Comparing the two sets of coordinate values, the measurement deviation from measuring point 1 to measuring point 6 is:

[0021]

[0022] When its error is less than the accuracy requirement, that is

[0023]

[0024] Where ε represents the accuracy requirement;

[0025] Take the average value As the coordinates of the measuring points in the hexagonal module unit, the measuring point coordinates are:

[0026] X′ f =(x1,x2,x3,x4,x5,x6)

[0027] Y f ′=(y1,y2,y3,y4,y5,y6)

[0028] Z′ f =(z1,z2,z3,z4,z5,z6).

[0029] Furthermore, the coordinates of all boundary points of the antenna are calculated based on the coordinates of the measurement points, and denoted as...

[0030]

[0031] Where n is the number of boundary points.

[0032] Furthermore, step 6, the calculation of the antenna assembly module surface accuracy, specifically involves:

[0033] The hexagonal module unit uses a cable net structure to form a parabola. According to the force balance equation, the nodal coordinates and prestress of the cable net structure satisfy the following:

[0034]

[0035] Where C is the matrix of free node connections within a known cable net structure, C f It is the known boundary node connection matrix of the cable net structure, F is the known design stress, and X, Y, Z are the coordinate matrices of free nodes in the cable net structure. Free nodes are the nodes inside the cable net structure.

[0036] Substituting equation (4) into equation (5) yields the spatial coordinates of all free nodes. The root mean square (RMS) value of the free node deformation is used to characterize the surface accuracy. The node deformation is as follows:

[0037]

[0038] Where Δx, Δy, and Δz are the deviations between the calculated results obtained from equation (5) and the theoretical values, the surface accuracy of the i-th antenna assembly module is characterized as follows:

[0039]

[0040] Where N iLet be the number of free nodes within the i-th module.

[0041] Furthermore, the overall antenna profile accuracy calculation is specifically as follows:

[0042] The overall surface accuracy of the assembled antenna is characterized by the RMS values ​​of all free nodes:

[0043]

[0044] Where N is the total number of free nodes, i.e.:

[0045]

[0046] Where m is the number of antenna assembly modules, which can be transformed as follows:

[0047]

[0048] This allows the surface accuracy of the antenna assembly module to be inverted to the surface accuracy of the overall antenna.

[0049] Furthermore, when the following conditions are met:

[0050]

[0051] The antenna profile already meets the design requirements.

[0052] Compared with the prior art, the present invention has the following beneficial technical effects:

[0053] The surface measurement method of this invention can significantly reduce the number of on-orbit surface measurement points for ultra-large assembled antennas, reduce the complexity of the measurement system and the cost of equipment, and achieve accurate spatial three-dimensional coordinate measurement of multiple antenna assembly modules, in a short period of time, and across the entire field. Attached Figure Description

[0054] Figure 1 This is a flowchart of the pose measurement method for the ultra-large on-orbit assembled antenna module of the present invention;

[0055] Figure 2 This is a schematic diagram of the measuring device and measuring points of the present invention;

[0056] Figure 3 This is a schematic diagram of the pose measurement of the module of the present invention;

[0057] Figure 4 This is a schematic diagram of the boundary points of the present invention;

[0058] Figure 5 This is a schematic diagram of the cable net structure of the present invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0060] An ultra-large on-orbit assembled antenna is formed by assembling multiple antenna assembly modules into a single antenna. This embodiment discloses a method for measuring the profile of an ultra-large on-orbit assembled antenna, such as... Figure 1 As shown, it includes the following steps:

[0061] Step 1: Equipment Installation. Install the measuring equipment on the satellite and install reflective targets at the peripheral nodes of the antenna assembly module; that is, the measuring equipment is installed on the satellite, and the measuring targets are installed at the measuring points of the antenna assembly module (using the peripheral nodes as measuring points; these peripheral nodes are used for splicing with other antenna assembly modules; for example, in a hexagonal antenna assembly module, all six vertices are used as measuring points). The angle between the line connecting the measuring equipment and the measuring target and the horizontal direction should not be less than 10°. Figure 2 As shown.

[0062] Measurement equipment can include visual measurement, laser measurement, microwave measurement, etc.

[0063] Step 2: Establish satellite coordinate system: Using the satellite as a reference, establish satellite coordinate system C1. Based on the installation location information of the measuring equipment in Step 1, obtain the spatial coordinates of the measuring equipment relative to the satellite coordinate system.

[0064] Step 3: Calibrate the measuring equipment: Using a measuring target, establish a spatial coordinate system C2 for the measuring equipment with the measuring equipment as the origin. The measuring equipment then performs self-calibration based on its built-in algorithm.

[0065] Step 4: Measuring the Measurement Point Locations: All measurements on each antenna assembly module are divided into two groups, each group including at least three measurement points. The target reflection is measured at the measurement points on the antenna assembly module using the measuring equipment on the satellite. The three-dimensional coordinates of the two sets of measurement points in coordinate system C2 are measured, and the three-dimensional coordinates of the two sets of measurement points in coordinate system C1 are obtained through coordinate transformation. The two sets of coordinates are compared, and when the error is less than the required accuracy, the average value is taken as the coordinates of the measurement points on the antenna assembly module. Figure 3 As shown;

[0066] Step 5: Calculation of the boundary positions around the antenna assembly module: Since the truss around the antenna assembly module is a stiff member, the three-dimensional coordinates of all boundary points of the antenna assembly module in coordinate system C1 can be calculated based on the coordinates of the measuring points obtained in Step 4. A schematic diagram of the boundary points is shown below. Figure 4 As shown;

[0067] Step 6: Antenna assembly module surface accuracy calculation: Based on the spatial coordinates of all boundary points of the antenna assembly module and the surface design stress of the antenna assembly module, the internal surface spatial coordinates of the antenna assembly module are inverted to obtain the RMSi value characterizing the surface accuracy of the antenna assembly module, that is, the root mean square value of the i-th antenna assembly module.

[0068] Step 7: Overall antenna profile accuracy calculation: Based on the RMSi value of each antenna assembly module, calculate the RMS value that characterizes the overall profile accuracy of the assembled antenna.

[0069] Step 8: Compare and verify with the antenna electrical performance indicators. The measurement ends when the antenna operation requirements are met. Otherwise, adjust the shape according to the measured value and remeasure. That is, check whether the RMS value meets the requirements. If the requirements are met, check the antenna electrical performance. If the on-orbit service performance is met, the measurement ends. If not, adjust the module spatial position according to the measured value and return to step 3.

[0070] Example:

[0071] This invention discloses a method for measuring the profile of an extremely large on-orbit assembled antenna, which solves the technical challenge of synchronous, short-time measurement of the profile of a very large aperture assembled antenna during on-orbit service. Figure 1 As shown, in order to meet the requirements of full-field measurement in a short time, a combination of methods such as visual measurement, laser measurement, and microwave measurement can be used for measurement. The specific method should be selected according to the configuration of the space assembly module and the mission requirements.

[0072] Based on the satellite's characteristics, it is proposed to design an extension arm on the satellite (when the distance and angle between the satellite and the antenna assembly module meet the measurement requirements, the measuring equipment can be directly installed on the satellite; when the distance and angle between the satellite and the antenna assembly module do not meet the measurement requirements, an extension arm can be designed on the satellite, and the measuring equipment can be installed on the extension arm) to ensure that the measurement distance and angle meet the requirements. A schematic diagram of the measuring equipment and measurement points is shown below. Figure 2 As shown.

[0073] The measuring equipment must first be calibrated. Considering that the antenna assembly reflector needs to match the position of the star, multiple calibration points are pre-designed on the star. The measuring equipment first measures the calibration points on the star's position to perform automatic calibration.

[0074] The antenna assembly module in this embodiment is formed by connecting multiple hexagonal module units sequentially, such as... Figure 2 and Figure 3As shown, hexagonal module units with at least one ring around the edge of the antenna assembly module are selected as the module under test. Measurement points are set at each vertex of the hexagon (the number of measurement points can be increased or decreased according to task requirements). The spatial position of the hexagonal plane can be determined based on the spatial coordinates of three points on a hexagon; therefore, measurement point group a is selected as measurement points 1, 2, and 3, and measurement point group b is selected as measurement points 4, 5, and 6. Based on the geometric position of the hexagonal module units, the spatial coordinates of all six measurement points of the two antenna modules can be calculated using the measured values, denoted as A and B.

[0075]

[0076] Comparing the two sets of coordinate values, the measurement deviation from measuring point 1 to measuring point 6 is:

[0077]

[0078] When its error is less than the accuracy requirement, that is

[0079]

[0080] Where ε represents the accuracy requirement.

[0081] Take the average value The flowchart for the three-dimensional coordinates of the measurement points of the hexagonal module unit is as follows: Figure 3 As shown, the coordinates can be denoted as:

[0082]

[0083] If the truss surrounding the antenna assembly module is a rigid member, then the coordinates of all boundary points of the antenna can be calculated based on the three-dimensional coordinates of the measuring points, such as... Figure 4 As shown, denoted as

[0084]

[0085] Where n is the number of boundary points.

[0086] The following calculation addresses the surface accuracy within the module. A cable net structure is used to form a parabolic surface within the hexagonal module. A schematic diagram of the cable net structure is shown below. Figure 5 As shown. According to the force balance equation, the nodal coordinates and prestress of the cable-net structure satisfy:

[0087]

[0088] Where C is the matrix of free node connections within a known cable net structure, C f This is the known boundary node connection matrix of the cable net structure, F is the known design stress, and X, Y, Z are the coordinate matrices of the free nodes within the cable net structure. Free nodes are, for example,... Figure 5 The internal nodes are shown.

[0089] Substituting equation (4) into equation (5) yields the spatial coordinates of all free nodes. The surface accuracy is generally characterized by the root mean square (RMS) value of the free node deformation. The node deformation is...

[0090]

[0091] Where Δx, Δy, and Δz are the deviations between the calculated results obtained from equation (5) and the theoretical values, the surface accuracy of the i-th antenna assembly module can be characterized as:

[0092]

[0093] Where N i Let be the number of free nodes within the i-th module.

[0094] The overall surface accuracy of the assembled antenna can be characterized by the RMS values ​​of all free nodes:

[0095]

[0096] Where N is the total number of free nodes, i.e.:

[0097]

[0098] Where m is the number of antenna assembly modules, which can be transformed as follows:

[0099]

[0100] This allows us to inversely determine the surface accuracy of the antenna assembly module to the overall antenna surface accuracy. Now, we evaluate the surface RMS value, which must satisfy the following conditions:

[0101]

[0102] The antenna profile has met the design requirements. At this point, the antenna's electrical performance is verified. If it meets the service requirements, the measurement is complete. If it does not, the influence of factors such as high and low temperatures in orbit on the antenna profile is considered. Based on the measurement results, the antenna assembly module is adjusted and the measurement is repeated until the antenna's in-orbit electrical performance requirements are met.

[0103] This invention integrates a set of methods for measuring the on-orbit profile of extremely large assembled antennas. Its advantage is that it can realize multi-module full-field synchronous measurement in a space environment, accurately predict the accuracy of the on-orbit antenna profile, and lay the foundation for on-orbit adjustment of assembled antennas.

[0104] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

Claims

1. A method for measuring the profile of an extremely large on-orbit assembled antenna, characterized in that: include: Step 1: Equipment Installation: Install the measuring equipment on the satellite body, and install measuring targets at all measuring points of each antenna assembly module; Step 2: Establish satellite coordinate system: Using the satellite as a reference, establish satellite coordinate system C1. Based on the installation location information of the measuring equipment in Step 1, obtain the spatial coordinates of the measuring equipment relative to the satellite coordinate system. Step 3: Calibrate the measuring equipment: Using a measuring target, establish a spatial coordinate system C2 for the measuring equipment with the measuring equipment as the origin. The measuring equipment then performs self-calibration based on its built-in algorithm. Step 4: Measure the position of the measurement points: All measurements on each antenna assembly module are divided into two groups, each group including at least three measurement points. The target reflection is measured at the measurement points of the antenna assembly module using the measurement equipment on the satellite. The three-dimensional coordinates of the two groups of measurement points in coordinate system C2 are measured, and the three-dimensional coordinates of the two groups of measurement points in coordinate system C1 are obtained through coordinate transformation. The three-dimensional coordinates of the two groups of measurement points in coordinate system C1 are compared. When the error is less than the accuracy requirement, the average value is taken as the measurement point coordinates of the antenna assembly module. Step 5: Calculate the boundary position of the antenna assembly module: Based on the coordinates of the measurement points of the antenna assembly module obtained in Step 4, calculate the three-dimensional coordinates of all boundary points of the antenna assembly module in coordinate system C1; Step 6: Antenna assembly module surface accuracy calculation: Based on the spatial coordinates of all boundary points of the antenna assembly module and the surface design stress of the antenna assembly module, the internal surface spatial coordinates of the antenna assembly module are inverted to obtain the RMSi value characterizing the surface accuracy of the antenna assembly module, that is, the root mean square value of the i-th antenna assembly module. Step 7: Overall antenna profile accuracy calculation: Based on the RMSi value of each antenna assembly module, calculate the RMS value that characterizes the overall profile accuracy of the assembled antenna. Step 8: Compare and verify with the antenna electrical performance indicators. The measurement ends when the antenna operation requirements are met. Otherwise, adjust the shape according to the measured value and remeasure. That is, check whether the RMS value meets the requirements. If the requirements are met, check the antenna electrical performance. If the on-orbit service performance is met, the measurement ends. If not, adjust the module spatial position according to the measured value and return to step 3.

2. The method for measuring the profile of an ultra-large on-orbit assembled antenna according to claim 1, characterized in that: When installing the equipment, the angle between the line connecting the measuring target and the horizontal direction should not be less than 10°.

3. The method for measuring the profile of an ultra-large on-orbit assembled antenna according to claim 1, characterized in that: The measuring device is a visual measuring device, a microwave measuring device, or a laser measuring device.

4. The method for measuring the profile of an ultra-large on-orbit assembled antenna according to claim 1, characterized in that: Step 4, measuring the location of the measuring point, specifically involves: The antenna assembly module is formed by connecting multiple hexagonal module units sequentially. At least one ring of hexagonal module units at the edge of the antenna assembly module's surface is selected as the module under test, and measurement points are set at the vertices of each hexagon. The spatial position of the hexagonal plane can be determined based on the spatial coordinates of three points on a hexagon; therefore, measurement point group a is selected as measurement points 1, 2, and 3, and measurement point group b is selected as measurement points 4, 5, and 6. Based on the geometric position of the hexagonal module units, the spatial coordinates of all six measurement points of the two antenna modules are calculated using the measured values ​​and denoted as A and B. Comparing the two sets of coordinate values, the measurement deviation from measuring point 1 to measuring point 6 is: When its error is less than the accuracy requirement, that is Where ε represents the accuracy requirement; Take the average value As the coordinates of the measuring points in the hexagonal module unit, the measuring point coordinates are: X′ f =(x1,x2,x3,x4,x5,x6) Y f (y1,y2,y3,y4,y5,y6) WITH' f =(z1,z2,z3,z4,z5,z6)。 5. The method for measuring the profile of an ultra-large on-orbit assembled antenna according to claim 4, characterized in that: The coordinates of all boundary points of the antenna are calculated based on the coordinates of the measurement points, and denoted as follows: Where n is the number of boundary points.

6. The method for measuring the profile of an ultra-large on-orbit assembled antenna according to claim 5, characterized in that: Step 6, the calculation of the antenna assembly module surface accuracy, specifically involves: The hexagonal module unit uses a cable net structure to form a parabola. According to the force balance equation, the nodal coordinates and prestress of the cable net structure satisfy the following: Where C is the matrix of free node connections within a known cable net structure, C f It is the known boundary node connection matrix of the cable net structure, F is the known design stress, and X, Y, Z are the coordinate matrices of free nodes in the cable net structure. Free nodes are the nodes inside the cable net structure. Substituting equation (4) into equation (5) yields the spatial coordinates of all free nodes. The root mean square (RMS) value of the free node deformation is used to characterize the surface accuracy. The node deformation is as follows: Where Δx, Δy, and Δz are the deviations between the calculated results obtained from equation (5) and the theoretical values, the surface accuracy of the i-th antenna assembly module is characterized as follows: Where N i Let be the number of free nodes within the i-th module.

7. The method for measuring the profile of an ultra-large on-orbit assembled antenna according to claim 6, characterized in that: The overall antenna's surface accuracy calculation is specifically as follows: The overall surface accuracy of the assembled antenna is characterized by the RMS values ​​of all free nodes: Where N is the total number of free nodes, i.e.: Where m is the number of antenna assembly modules, which can be transformed as follows: This allows the surface accuracy of the antenna assembly module to be inverted to the surface accuracy of the overall antenna.

8. The method for measuring the profile of an ultra-large on-orbit assembled antenna according to claim 7, characterized in that: When the following conditions are met: The antenna profile already meets the design requirements.

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