Large-scale space structure thermal deformation measuring device and measuring method

Abstract

The application provides a large-scale space structure thermal deformation measuring device for measuring six-degree-of-freedom relative poses between a first end face and a second end face of a measured space structure, comprising an environment simulation container, a first digital speckle interferometry measuring unit, a second digital speckle interferometry measuring unit, an absolute distance measuring module, and a control and processing unit. Through specific system layout and data fusion, the application can realize high-precision thermal deformation measurement of a large-scale space structure under a vacuum high-low temperature environment.

Description

Technical Field

[0001] This application relates to the field of precision optical measurement technology, and more specifically, to a device and method for measuring the thermal deformation of large-scale spatial structures. Background Technology

[0002] Spacecraft deployable arms, space antenna support structures, and other large-scale space structures may experience significant temperature variations during operation, such as extreme high and low temperature alternations. This can lead to thermal deformation, affecting the deployment accuracy, installation accuracy, or operational stability of the space structure. Therefore, it is necessary to measure thermal deformation during ground testing. Accurate measurement of thermal deformation, especially end-face attitude changes, is crucial for evaluating structural performance and verifying design specifications. However, existing attitude measurement devices and methods have many limitations in measuring the thermal deformation of large-scale structures under vacuum high and low temperature environments. Summary of the Invention

[0003] This application provides a device and method for measuring the thermal deformation of large-scale spatial structures. Through a specific system layout and data fusion, it enables high-precision measurement of the thermal deformation of large-scale spatial structures under vacuum high and low temperature environments.

[0004] To achieve the above objectives, the embodiments of this application provide the following technical solutions.

[0005] In a first aspect, embodiments of this application provide a large-scale spatial structure thermal deformation measurement device for measuring the six-degree-of-freedom relative pose between a first end face and a second end face of a measured spatial structure. The device includes: an environmental simulation container with an internal accommodating space for mounting the measured spatial structure; the environmental simulation container having a first side and a second side arranged opposite to each other; the first side having a first optical window opposite to the first end face; and the second side having a second optical window opposite to the second end face; a first digital speckle interferometry unit disposed outside the first optical window for acquiring first full-field displacement data of the first end face through the first optical window; a second digital speckle interferometry unit disposed outside the second optical window for acquiring second full-field displacement data of the second end face through the second optical window; an absolute distance measurement module for obtaining absolute distance data corresponding to the distance between the first end face and the second end face; and a control and processing unit for obtaining the six-degree-of-freedom relative pose between the first end face and the second end face based on the first full-field displacement data, the second full-field displacement data, and the absolute distance data.

[0006] In some embodiments, the absolute ranging module includes: a first absolute ranging unit and a second absolute ranging unit disposed on the first side; a first reflective target disposed on the first end face, the mounting area of ​​the first reflective target being located within the measurement range of the first digital speckle interferometry unit; and a second reflective target disposed on the second end face, the mounting area of ​​the second reflective target being located within the measurement range of the second digital speckle interferometry unit. The first absolute ranging unit is used to perform absolute distance measurement on the first reflective target, and the second absolute ranging unit is used to perform absolute distance measurement on the second reflective target to obtain absolute distance data corresponding to the distance between the first end face and the second end face.

[0007] In some embodiments, the absolute ranging module is a dual-comb absolute ranging module; the first reflective target uses a first cornerstone prism, and the second reflective target uses a second cornerstone prism; the first cornerstone prism and the second cornerstone prism are respectively disposed at the edge positions of the first end face and the second end face, the reflective surfaces of the first cornerstone prism and the second cornerstone prism are both facing the side where the light source of the dual-comb absolute ranging module is located, and the installation positions of the first cornerstone prism and the second cornerstone prism on the corresponding end faces are staggered from each other.

[0008] In some embodiments, the control and processing unit is connected to the first digital speckle interferometry unit, the second digital speckle interferometry unit, and the absolute ranging module, respectively. The control and processing unit is configured to determine the first local deformation data of the mounting area of ​​the first reflective target and the second local deformation data of the mounting area of ​​the second reflective target based on the first full-field displacement data and the second full-field displacement data, respectively; and to correct the absolute distance data based on the first local deformation data and the second local deformation data; and to calibrate the axial relative displacement between the first end face and the second end face based on the corrected absolute distance data, and to combine the calibrated axial relative displacement with two lateral relative displacements and three angular displacements determined based on the first full-field displacement data and the second full-field displacement data to obtain a six-degree-of-freedom relative pose between the first end face and the second end face.

[0009] In some embodiments, the environment simulation container is a vacuum high and low temperature container, used to create a vacuum high and low temperature alternating environment within the containment space.

[0010] In some embodiments, the first optical window includes a light-transmitting area through which the measurement light of the first digital speckle interferometry unit and the measurement light of the absolute ranging module pass; the second optical window includes a plurality of light-transmitting areas spaced apart, the plurality of light-transmitting areas corresponding to the respective measurement optical paths of the second digital speckle interferometry unit.

[0011] In some embodiments, the system further includes an air-floating vibration isolation platform, wherein the environmental simulation container, the first digital speckle interferometry unit, the second digital speckle interferometry unit, and the absolute ranging module are disposed on the air-floating vibration isolation platform.

[0012] Secondly, this application provides a method for measuring the thermal deformation of a large-scale spatial structure, comprising: before the measured spatial structure undergoes thermal deformation, acquiring the initial absolute distance between a first end face and a second end face of the measured spatial structure; during the thermal deformation of the measured spatial structure, acquiring first full-field displacement data of the first end face using a first digital speckle interferometry unit, acquiring second full-field displacement data of the second end face using a second digital speckle interferometry unit, and acquiring current absolute distance data corresponding to the distance between the first end face and the second end face using an absolute ranging module; extracting first local deformation data of the installation area of ​​the first reflective target from the first full-field displacement data based on the installation position of the first reflective target on the first end face, and based on... The installation position of the second reflective target on the second end face is determined. Second local deformation data of the installation area of ​​the second reflective target is extracted from the second full-field displacement data. The current absolute distance data is corrected based on the first and second local deformation data. The axial relative displacement between the first and second end faces is calibrated based on the change in the corrected current absolute distance data relative to the initial absolute distance. The calibrated axial relative displacement is then combined with two lateral relative displacements and three angular displacements determined based on the first and second full-field displacement data to obtain a six-degree-of-freedom relative pose between the first and second end faces.

[0013] In some embodiments, the measured spatial structure is disposed inside a vacuum high-low temperature container, and the measurement method further includes: heating and / or cooling the measured spatial structure according to a predetermined temperature change process; at the measurement node when the measured spatial structure reaches a predetermined temperature, synchronously triggering the first digital speckle interferometry measurement unit and the second digital speckle interferometry measurement unit to perform full-field displacement measurement, and acquiring the current absolute distance data output by the absolute ranging module at the measurement node, so that the first full-field displacement data, the second full-field displacement data and the current absolute distance data correspond to each other in time.

[0014] In some embodiments, the current absolute distance data is corrected according to the following formula: L corr = L abs - (δ zc1 + δ zc2 ); Among them, L corr L is the corrected absolute distance between the first and second end faces. abs For the absolute distance data, δ zc1 Let δ be the first local deformation. zc2 The second local deformation amount; the change in the corrected current absolute distance data relative to the initial absolute distance is determined according to the following formula: ΔL corr = L corr - L0; Where, ΔL corr L0 represents the change in absolute distance, and L0 represents the initial absolute distance.

[0015] Compared with existing technologies, this application acquires full-field displacement data of the two end faces of the measured spatial structure through a digital speckle interferometry unit, which can determine the six-degree-of-freedom pose changes and local surface deformation of the end faces, thereby reducing the influence of local surface deformation on the pose measurement results. At the same time, the local deformation of the reflective target installation area is extracted from the full-field displacement data, and the absolute distance measurement result is corrected using the local deformation, which can reduce the distance measurement error introduced by thermal deformation of the reflective target installation area. Furthermore, the axial incremental displacement obtained by digital speckle interferometry is calibrated using the corrected absolute distance measurement result, realizing the complementarity of full-field incremental measurement and absolute distance measurement, which is beneficial to improving the accuracy and stability of six-degree-of-freedom thermal deformation measurement of large-scale spatial structures under vacuum high and low temperature environments. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 A schematic diagram of a large-scale spatial structure thermal deformation measurement device provided in an embodiment of this application; Figure 2 A partial structural schematic diagram of the first side of a large-scale spatial structure thermal deformation measuring device provided in an embodiment of this application; Figure 3A partial structural schematic diagram of the second side of a large-scale spatial structure thermal deformation measuring device provided in an embodiment of this application; Figure 4 A schematic diagram of the measurement optical path between the absolute ranging module and the first and second reflective targets provided in an embodiment of this application; Figure 5 This is a functional connection diagram of a measuring device provided in an embodiment of this application; Figure 6 A schematic flowchart of a measurement method provided in an embodiment of this application; Figure 7 A schematic diagram showing localized thermal deformation in the mounting area of ​​a reflective target according to an embodiment of this application; Figure 8 This is a schematic diagram of a data processing result display interface provided in an embodiment of this application.

[0018] In the attached diagram: 100. First digital speckle interferometry unit; 200. Second digital speckle interferometry unit; 300. Absolute ranging module; 310. First absolute ranging unit; 320. Second absolute ranging unit; 330. Absolute ranging signal processing unit; 340. First reflecting target; 350. Second reflecting target; 360. Optical fiber; 370. Communication cable; 400. Environmental simulation container; 410. First optical window; 420. Second optical window; 500. Air-bearing vibration isolation platform; 600. Control and processing unit; 610. Control host; 620. Display device; 630. Emergency stop device; 700. Measured spatial structure; 710. First end face; 720. Second end face; 110. First laser power supply; 120. Second laser power supply. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the application. The singular forms “a,” “said,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0021] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0022] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an apparatus or method that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an apparatus or method. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the apparatus or method that includes said element.

[0023] As described in the background section, large-scale space structures (such as those on the order of 10 meters) such as spacecraft deployable arms may experience extreme high and low temperature alternating environments during operation, causing thermal deformation. Accurately measuring the thermal deformation of large-scale space structures, especially the six-degree-of-freedom relative pose changes between the two end faces, is of great significance for evaluating structural performance and verifying design specifications.

[0024] Existing optical pose measurement methods mainly include laser tracking measurement, laser interferometry combined measurement, differential wavefront measurement, grating interferometry, and measurement methods combining laser ranging and photogrammetry. When these measurement methods are applied to the thermal deformation measurement of large-scale space structures in vacuum high and low temperature environments, they usually suffer from limitations such as the inability to decouple pose from surface deformation, error crosstalk, incremental measurement limitations, and high system complexity.

[0025] To address the aforementioned problems, one aspect of this application provides a large-scale spatial structure thermal deformation measurement device for measuring the six-degree-of-freedom relative pose between a first end face and a second end face of a measured spatial structure. The device includes: an environmental simulation container with an internal accommodating space for mounting the measured spatial structure; the environmental simulation container has a first side and a second side arranged opposite to each other; the first side has a first optical window opposite to the first end face, and the second side has a second optical window opposite to the second end face; a first digital speckle interferometry unit disposed outside the first optical window for acquiring first full-field displacement data of the first end face through the first optical window; a second digital speckle interferometry unit disposed outside the second optical window for acquiring second full-field displacement data of the second end face through the second optical window; an absolute distance measurement module for obtaining absolute distance data corresponding to the distance between the first end face and the second end face; and a control and processing unit for obtaining the six-degree-of-freedom relative pose between the first end face and the second end face based on the first full-field displacement data, the second full-field displacement data, and the absolute distance data.

[0026] The term "pose" as used in this application includes position and orientation. The six-degree-of-freedom pose of the measured end face can be represented by three linear displacements along three mutually perpendicular directions and three angular displacements about these three directions. Specifically, the length direction of the measured spatial structure can be defined as the axial direction, and the two directions perpendicular to the axial direction can be defined as the transverse directions.

[0027] The "full-field displacement data" referred to in this application refers to displacement data obtained at multiple measurement positions within a predetermined measurement area of ​​the measured end face, or phase data that can be used to determine the displacement data at the multiple measurement positions. The full-field displacement data can be used to determine the overall pose change of the measured end face, or to determine the deformation of different local areas of the measured end face.

[0028] refer to Figures 1 to 5 In some embodiments, the large-scale spatial structure thermal deformation measurement device includes an environmental simulation container 400, a first digital speckle interferometry measurement unit 100, a second digital speckle interferometry measurement unit 200, an absolute ranging module 300, and a control and processing unit 600.

[0029] The first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200 use Digital Speckle Pattern Interferometry (DSPI) to perform full-field displacement measurement. The first digital speckle interferometry unit 100 can be simply referred to as the first DSPI tester, and the second digital speckle interferometry unit 200 can be simply referred to as the second DSPI tester.

[0030] The environment simulation container 400 has an internal space for accommodating the measured spatial structure 700. The environment simulation container 400 has a first side and a second side arranged opposite to each other along the length of the measured spatial structure 700. The first side has a first optical window 410, and the second side has a second optical window 420. The first optical window 410 and the second optical window 420 may include one or more light-transmitting areas, the position and size of which are set according to the position and light transmission range of the corresponding measurement optical path. Specifically, in this embodiment, the first optical window 410 and the second optical window 420 are each an integral optical window. The light-transmitting area of ​​the first optical window 410 allows the measurement light of the first digital speckle interferometry unit 100 and the first and second measurement lights of the absolute ranging module 300 to pass through, while the light-transmitting area of ​​the second optical window 420 allows the measurement light of the second digital speckle interferometry unit 200 to pass through. In some other embodiments, the first optical window 410 and / or the second optical window 420 include a plurality of light-transmitting areas spaced apart. For example, the second optical window 420 may include five light-transmitting areas arranged in a cross shape, and the plurality of light-transmitting areas correspond to the corresponding measurement optical paths of the second digital speckle interferometry measurement unit 200.

[0031] The test space structure 700 is installed within the containment space of the environmental simulation container 400. The test space structure 700 has a first end face 710 and a second end face 720 disposed opposite each other along its length direction, the first end face 710 facing the first optical window 410 and the second end face 720 facing the second optical window 420. In some embodiments, the test space structure 700 is suspended horizontally within the containment space, and the length direction of the test space structure 700 is substantially consistent with the length direction of the environmental simulation container 400. Suspending the test space structure 700 within the environmental simulation container 400 allows the test space structure 700 to undergo environmental simulation testing and optical measurements without contacting external measuring components.

[0032] The first optical window 410 and the second optical window 420 allow corresponding measurement light to pass through, so that the measurement unit located outside the environmental simulation container 400 can perform non-contact measurement on the first end face 710 and the second end face 720.

[0033] In some embodiments, the environmental simulation container 400 is a vacuum high-low temperature container, used to provide a vacuum and high-low temperature alternating test environment for the space structure under test 700. The space structure under test 700 can be a spacecraft deployment arm, a space antenna support structure, a space camera support structure, or other large-scale space structures that require measurement of end-face thermal deformation and attitude changes. In one specific embodiment, the space structure under test 700 is a spacecraft deployment arm with a length of approximately 10m.

[0034] The first digital speckle interferometry measurement unit 100 is disposed outside the first optical window 410, and its measurement optical axis passes through the first optical window 410 toward the first end face 710. The first digital speckle interferometry measurement unit 100 is used to perform full-field displacement measurement on the first end face 710 to obtain full-field displacement data of the first end face 710.

[0035] The second digital speckle interferometry unit 200 is disposed outside the second optical window 420, and its measuring optical axis passes through the second optical window 420 toward the second end face 720. The second digital speckle interferometry unit 200 is used to perform full-field displacement measurement on the second end face 720 to obtain full-field displacement data of the second end face 720.

[0036] In this embodiment, the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200 are respectively arranged on opposite sides of the environmental simulation container 400, forming a dual-sided measurement layout. The measurement optical axes of the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200 are substantially coaxial and substantially parallel to the central axis of the measured spatial structure 700.

[0037] The absolute ranging module 300 is located on the first side of the environmental simulation container 400 and on the same side of the environmental simulation container 400 as the first digital speckle interferometry measurement unit 100, thus forming a system layout that combines dual-sided DSPI measurement with single-sided absolute ranging.

[0038] The absolute ranging module 300 includes an absolute ranging light source (not shown), a first absolute ranging unit 310, a second absolute ranging unit 320, an absolute ranging signal processing unit 330, a first reflective target 340, and a second reflective target 350.

[0039] The first absolute ranging unit 310 and the second absolute ranging unit 320 are both connected to the absolute ranging light source, which provides measuring light to the first absolute ranging unit 310 and the second absolute ranging unit 320. The first absolute ranging unit 310 forms a first ranging optical path, and the second absolute ranging unit 320 forms a second ranging optical path.

[0040] The first absolute ranging unit 310 and the second absolute ranging unit 320 are also connected to the absolute ranging signal processing unit 330 to transmit the measurement signals obtained by the first ranging optical path and the second ranging optical path to the absolute ranging signal processing unit 330. The absolute ranging signal processing unit 330 is used to process the measurement signals to obtain corresponding absolute distance data.

[0041] In some embodiments, the first absolute ranging unit 310 and the second absolute ranging unit 320 are respectively connected to the absolute ranging signal processing unit 330 via optical fiber 360. The absolute ranging signal processing unit 330 is connected to the control and processing unit 600 via communication cable 370 to transmit absolute distance data to the control and processing unit 600.

[0042] The first reflective target 340 is disposed on the first end face 710, and the second reflective target 350 is disposed on the second end face 720. The first absolute ranging unit 310 is disposed correspondingly to the first reflective target 340 to form a first ranging optical path; the second absolute ranging unit 320 is disposed correspondingly to the second reflective target 350 to form a second ranging optical path.

[0043] The first measuring light emitted by the first absolute ranging unit 310 enters the environmental simulation container 400 through the first optical window 410 and is incident on the first reflective target 340. After being reflected by the first reflective target 340, it returns to the first absolute ranging unit 310. The second measuring light emitted by the second absolute ranging unit 320 enters the environmental simulation container 400 through the first optical window 410 and propagates to the second reflective target 350. After being reflected by the second reflective target 350, it returns to the second absolute ranging unit 320.

[0044] The mounting area of ​​the first reflective target 340 is within the measurement range of the first digital speckle interferometry unit 100, and the mounting area of ​​the second reflective target 350 is within the measurement range of the second digital speckle interferometry unit 200. When acquiring the full-field displacement data of the corresponding end faces, the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200 can also monitor the local deformation of the corresponding reflective target mounting area.

[0045] In some embodiments, the absolute ranging module 300 is a dual-comb absolute ranging module, the absolute ranging light source is a dual-comb laser, and the absolute ranging signal processing unit 330 is a dual-comb signal processing unit. The dual-comb laser is used to generate two measurement beams, which are emitted from the first absolute ranging unit 310 and the second absolute ranging unit 320, respectively, and incident on the first reflecting target 340 and the second reflecting target 350, respectively.

[0046] The measurement light reflected from the first reflective target 340 and the second reflective target 350 is received by the first absolute ranging unit 310 and the second absolute ranging unit 320, respectively, and transmitted to the absolute ranging signal processing unit 330. The absolute ranging signal processing unit 330 obtains the absolute distance data corresponding to the first reflective target 340 and the second reflective target 350, respectively, based on the measurement light reflected from the first reflective target 340 and the second reflective target 350.

[0047] In some embodiments, the first reflective target 340 is a first corner bevel prism, and the second reflective target 350 is a second corner bevel prism. The first corner bevel prism and the second corner bevel prism are respectively installed at the edge positions of the first end face 710 and the second end face 720, and the reflective surfaces of the two corner bevel prisms both face the side where the absolute ranging light source is located.

[0048] The first and second corner prisms are installed at offset positions on their respective end faces so that the first and second measuring lights can be incident on their respective corner prisms.

[0049] In other embodiments, the absolute ranging module 300 may also employ femtosecond laser absolute ranging, laser tracking absolute ranging, or other ranging methods capable of providing absolute distance data. Accordingly, the absolute ranging light source, the first absolute ranging unit 310, the second absolute ranging unit 320, and the absolute ranging signal processing unit 330 may be configured according to the absolute ranging method employed.

[0050] In some embodiments, the large-scale spatial structure thermal deformation measurement device further includes an air-floating vibration isolation platform 500. The environmental simulation container 400, the first digital speckle interferometry measurement unit 100, the second digital speckle interferometry measurement unit 200, and the absolute ranging module 300 are disposed on the same air-floating vibration isolation platform 500 to reduce the influence of external vibration on the measurement results. As a specific example, the environmental simulation container 400 is horizontally disposed in the middle of the air-floating vibration isolation platform 500, the first digital speckle interferometry measurement unit 100 and the absolute ranging module 300 are disposed on the first side of the environmental simulation container 400, and the second digital speckle interferometry measurement unit 200 is disposed on the second side of the environmental simulation container 400, thereby enabling the environmental simulation container 400 and the measurement units on both sides to be jointly disposed on the same air-floating vibration isolation platform 500.

[0051] The control and processing unit 600 is communicatively connected to the first digital speckle interferometry unit 100, the second digital speckle interferometry unit 200, the absolute ranging module 300, and the environmental simulation container 400, respectively, and is used to realize synchronous triggering control, data acquisition, data processing, calculation and storage of each measurement module.

[0052] In some embodiments, reference Figure 5The control and processing unit 600 includes a control host 610, a display device 620, and a synchronous trigger control circuit. The control host 610 is connected to the first digital speckle interferometry unit 100, the second digital speckle interferometry unit 200, the absolute ranging signal processing unit 330, the absolute ranging light source, and the environmental simulation container 400 via corresponding communication interfaces. The synchronous trigger control circuit is connected to the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200, and is used to send trigger signals and gating signals to the two digital speckle interferometry units.

[0053] In one specific embodiment, the control host 610 is connected to the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200 via a USB 3.0 interface, to the absolute ranging signal processing unit 330 via an Ethernet interface, and to the absolute ranging light source and environmental simulation container 400 via a serial communication interface. The above-described communication interface is only one specific implementation; other communication interfaces capable of transmitting control commands and measurement data can be used depending on the interface type of each measurement module.

[0054] In some embodiments, the control and processing unit 600 further includes an emergency stop device 630. The emergency stop device 630 is used to cut off the power supply to the corresponding device when the measuring device malfunctions. The first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200 may also be configured with corresponding laser power supplies to power the corresponding laser sources.

[0055] In some embodiments, the process of measuring the thermal deformation of the space structure 700 under test using the above-mentioned measuring device includes an initial calibration stage and a dynamic measurement stage.

[0056] In the initial calibration stage, before the start of the thermal deformation test, a laser tracker is used to measure the initial pose of the first end face 710 and the second end face 720 of the space structure under test 700, and the initial pose parameters of the first end face 710 and the second end face 720 in the global coordinate system are obtained. The initial pose parameters are used as the initial reference for subsequent measurement and data fusion.

[0057] In some embodiments, the correspondence between the measurement coordinate system of the first digital speckle interferometry unit 100, the measurement coordinate system of the second digital speckle interferometry unit 200, and the global coordinate system is established through initial calibration, so as to convert the measurement data obtained by the two digital speckle interferometry units to the same coordinate system.

[0058] During the initial calibration phase, the absolute ranging module 300 can also acquire the initial absolute distance data corresponding to the first reflective target 340 and the second reflective target 350 respectively, and determine the initial distance L0 between the first end face 710 and the second end face 720 based on the initial absolute distance data.

[0059] During the dynamic measurement phase, the environmental simulation container 400 creates a vacuum high and low temperature environment inside itself and heats and / or cools the measured space structure 700 according to a predetermined temperature change process. During the vacuum high and low temperature environment simulation, data is collected at predetermined time intervals or at measurement nodes when the measured space structure 700 reaches a predetermined temperature.

[0060] At each measurement node, the first digital speckle interferometry measurement unit 100 and the second digital speckle interferometry measurement unit 200 simultaneously perform full-field displacement measurements on the first end face 710 and the second end face 720 through the first optical window 410 and the second optical window 420, respectively.

[0061] The first digital speckle interferometry unit 100 acquires six-degree-of-freedom pose change data of the first end face 710 relative to the first digital speckle interferometry unit 100 and full-field displacement distribution data of the first end face 710. The second digital speckle interferometry unit 200 acquires six-degree-of-freedom pose change data of the second end face 720 relative to the second digital speckle interferometry unit 200 and full-field displacement distribution data of the second end face 720.

[0062] The control and processing unit 600 performs coordinate transformation and synthesis on the data obtained by the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200 according to the coordinate correspondence determined by the initial calibration, so as to obtain six-degree-of-freedom relative pose change data between the first end face 710 and the second end face 720.

[0063] While the two digital speckle interferometry units perform full-field displacement measurements, the absolute ranging module 300 emits two measurement beams through the first absolute ranging unit 310 and the second absolute ranging unit 320. The first measurement beam is incident on the first reflecting target 340 to obtain the first absolute distance data corresponding to the first reflecting target 340; the second measurement beam is incident on the second reflecting target 350 to obtain the second absolute distance data corresponding to the second reflecting target 350. The absolute ranging signal processing unit 330 determines the absolute distance data between the first end face 710 and the second end face 720 based on the first and second absolute distance data.

[0064] In an embodiment where the absolute ranging module 300 is a dual-comb absolute ranging module, the dual-comb laser emits two measurement beams from the first side of the environmental simulation container 400. The two measurement beams are emitted through the first absolute ranging unit 310 and the second absolute ranging unit 320, respectively, and detect the absolute distance between the first corner prism and the second corner prism, so as to obtain the absolute distance data between the first end face 710 and the second end face 720.

[0065] Digital speckle interferometry (DII) is a full-field incremental measurement method that can acquire the six-degree-of-freedom pose changes and full-field displacement distribution of the measured end face with high resolution. However, it may accumulate errors during long-term continuous measurements, and the continuous measurement reference may be lost when the measurement optical path is interrupted. The absolute ranging module 300 can provide absolute distance data and has the characteristic of stable measurement reference. However, the absolute ranging module 300 performs point distance measurement through a reflective target set on the measured end face. When temperature changes cause local deformation of the reflective target's mounting area, the obtained absolute distance data may simultaneously include the overall displacement of the end face and the local deformation of the reflective target's mounting area. Furthermore, other degrees of freedom motion of the measured end face may also affect the distance data obtained along the ranging optical path.

[0066] To mitigate the impact of the aforementioned factors, this application employs a dual-scale calibration method. The first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200 serve as high-precision scales, simultaneously measuring the six-degree-of-freedom pose changes and full-field deformation of the first end face 710 and the second end face 720, while also monitoring the local deformation of the mounting areas of the first reflecting target 340 and the second reflecting target 350. The absolute ranging module 300 serves as a calibration scale, providing an absolute distance reference for the axial relative displacement between the first end face 710 and the second end face 720, and is used to calibrate the axial cumulative error that may occur during the digital speckle interferometry measurement at each measurement node.

[0067] Specifically, the control and processing unit 600 extracts the first local deformation data of the mounting area of ​​the first reflective target 340 from the full-field displacement data of the first end face 710 obtained by the first digital speckle interferometry measurement unit 100; and extracts the second local deformation data of the mounting area of ​​the second reflective target 350 from the full-field displacement data of the second end face 720 obtained by the second digital speckle interferometry measurement unit 200.

[0068] The control and processing unit 600 uses the first local deformation data and the second local deformation data to correct the absolute distance data obtained by the absolute ranging module 300, so as to reduce the impact of local deformation of the installation area of ​​the first reflective target 340 and the second reflective target 350 on the absolute distance data.

[0069] Subsequently, the control and processing unit 600 uses the corrected absolute distance data as a reference to perform absolute calibration on the axial relative displacements obtained by the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200. The control and processing unit 600 then combines the calibrated axial relative displacements with the linear and angular displacements in other directions obtained by digital speckle interferometry to output the fused six-degree-of-freedom relative pose data between the first end face 710 and the second end face 720.

[0070] Digital speckle interferometry provides high-precision full-field displacement data of the end face and is used to correct the influence of local deformation in the reflective target installation area on the absolute ranging results. On the other hand, the absolute ranging module 300 provides an axial absolute distance reference and is used to calibrate the axial cumulative error in digital speckle interferometry, thereby forming a mutually calibrated data fusion relationship.

[0071] In some implementations, a joint optimization approach can also be used for data fusion. The control and processing unit 600 uses the full-field displacement data obtained by the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200, along with the absolute distance data obtained by the absolute ranging module 300, as joint constraints, and solves the six-degree-of-freedom relative pose between the first end face 710 and the second end face 720 through an optimization algorithm.

[0072] In other embodiments, a weighted fusion method may also be used. The control and processing unit 600 determines the fusion weights of the two types of measurement data based on the uncertainty or signal quality corresponding to the digital speckle interferometry measurement data and the absolute distance data, and obtains the fused measurement result according to the fusion weights.

[0073] In other implementations, a time-series recursive approach can also be used. The control and processing unit 600 establishes a time-series model between the digital speckle interferometry data and the absolute distance data, and uses the absolute distance data to estimate and compensate for the cumulative error generated during the digital speckle interferometry process online.

[0074] At the hardware level, the control and processing unit 600 coordinates the working timing of the first digital speckle interferometry measurement unit 100, the second digital speckle interferometry measurement unit 200, and the absolute ranging module 300 through a synchronous trigger control circuit. For measurement modules with different sampling frequencies, the data of each measurement module can be time-aligned according to the synchronous trigger signal, the acquisition time, or the data timestamp, so that the data participating in the calculation of the same measurement node correspond to the same or similar thermal deformation states.

[0075] In some embodiments, the control and processing unit 600 is provided with a data acquisition and control system. The data acquisition and control system is used to complete the communication and coordination between the control and processing unit 600 and each measurement module, including a setting module, a calibration module, and an acquisition module.

[0076] Specifically, the setting module is used to set the operating parameters of the first digital speckle interferometry unit 100, the second digital speckle interferometry unit 200, the absolute ranging module 300, and the environmental simulation container 400, so that each measurement module is in a predetermined measurement state. The calibration module is used to calibrate the measurement field of view of the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200, establish the mapping relationship between image coordinates and world coordinates, and provide calibration parameters for converting the pose data of the two end faces to the same coordinate system. The acquisition module is used to acquire the operating state and temperature information of the environmental simulation container 400, and perform temperature trigger control based on the temperature information. When the measured spatial structure 700 reaches the set temperature point and meets the predetermined measurement state, the acquisition module triggers the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200 to perform full-field displacement measurement through the synchronous trigger control circuit, and acquires the absolute distance data output by the absolute ranging module 300, and saves the data obtained by each measurement module.

[0077] The following is a detailed explanation of thermal deformation measurement under vacuum high and low temperature environments using a specific example. This embodiment employs the aforementioned large-scale space structure thermal deformation measurement device to measure the thermal deformation of a spacecraft deployment arm approximately 10m in length under vacuum high and low temperature environments. The environmental simulation container 400 is a vacuum high and low temperature container, the absolute ranging module 300 is a dual-comb absolute ranging module, and both the first reflective target 340 and the second reflective target 350 utilize cornerstone prisms.

[0078] The tested deployable arm is suspended horizontally inside the vacuum high-low temperature container. Its right end face serves as the first end face 710 and faces the first optical window 410, while its left end face serves as the second end face 720 and faces the second optical window 420. For the remaining hardware arrangement and connections, please refer to the aforementioned implementation method and... Figures 1 to 5 .

[0079] Before performing thermal deformation measurements, a laser tracker is used to measure the initial poses of the first end face 710 and the second end face 720 of the measured spatial structure 700, obtaining the initial pose parameters of the two end faces in the global coordinate system. These initial pose parameters are then used to establish the initial reference for subsequent measurements and data fusion. A dual-comb absolute ranging module 300 measures the initial absolute distances corresponding to the first and second corner cube prisms, and determines the initial distance L0 between the first end face 710 and the second end face 720 based on these initial absolute distances.

[0080] After initial calibration, the vacuum system is activated to evacuate the vacuum level in the high and low temperature container to a level better than 1.3 × 10⁻³ Pa; the heat sink system is activated to reduce the heat sink background temperature to no higher than 100 K; then the space structure under test 700 is heated and cooled according to the predetermined temperature change curve, so that the space structure under test 700 undergoes a temperature cycle from -80℃ to 100℃.

[0081] The data acquisition software sends query commands to the vacuum high-low temperature container at predetermined time intervals to obtain the operating status of the vacuum high-low temperature container and the temperature information of the measured space structure 700. When the measured space structure 700 reaches the set temperature point and meets the predetermined measurement conditions, the data acquisition software sends a measurement command to the synchronous trigger control circuit. The synchronous trigger control circuit synchronously triggers the first digital speckle interferometry measurement unit 100 and the second digital speckle interferometry measurement unit 200 to perform full-field displacement measurement.

[0082] The data acquisition software reads and saves the absolute distance data output by the dual optical comb signal processing unit 330, and reads and saves the six-degree-of-freedom pose change data and full-field displacement data output by the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200, respectively.

[0083] The interface of the data acquisition software may include a function panel area, a work directory area, an information prompt area, and a preview area. The function panel area is used to set measurement parameters and execute measurement operations; the work directory area is used to display and manage the acquired data files; the information prompt area is used to display the working status of the measuring device and prompt information; and the preview area is used to display the phase diagram generated during the measurement process in real time, so that the operator can judge the current measurement status.

[0084] Data analysis software processes and integrates the collected data. For example... Figure 6 As shown, the data fusion calculation includes steps such as deformation extraction of the cornerstone prism mounting area, correction of dual-comb ranging error, and six-degree-of-freedom data calibration. Specifically, this application embodiment provides a method for measuring the thermal deformation of large-scale spatial structures, including the following steps: S100, before the start of the thermal deformation test, obtain the initial absolute distance L0 between the first end face 710 and the second end face 720 of the tested spatial structure 700.

[0085] In some implementations, a laser tracker can be used to measure the initial pose of the first end face 710 and the second end face 720 to obtain the initial pose parameters of the first end face 710 and the second end face 720 in the global coordinate system, so as to establish the initial pose reference of the two end faces.

[0086] S200, during the thermal deformation of the measured spatial structure 700, the first digital speckle interferometry measurement unit 100 performs full-field displacement measurement on the first end face 710 to obtain first full-field displacement data; the second digital speckle interferometry measurement unit 200 performs full-field displacement measurement on the second end face 720 to obtain second full-field displacement data; the absolute distance measurement module 300 performs absolute distance measurement on the first reflection target 340 set on the first end face 710 and the second reflection target 350 set on the second end face 720 to obtain absolute distance data L corresponding to the distance between the first end face 710 and the second end face 720. abs .

[0087] In some embodiments, the first digital speckle interferometry unit 100, the second digital speckle interferometry unit 200, and the absolute distance measurement module 300 are synchronously triggered at predetermined measurement nodes to obtain the first full-field displacement data, the second full-field displacement data, and the absolute distance data L. abs They correspond to each other in time.

[0088] S300, based on the installation position of the first reflective target 340 on the first end face 710, extract the first local deformation δ of the area corresponding to the installation position of the first reflective target 340 from the first full-field displacement data. zc1 Based on the installation position of the second reflective target 350 on the second end face 720, the second local deformation δ of the area corresponding to the installation position of the second reflective target 350 is extracted from the second full-field displacement data. zc2 .

[0089] The first reflecting target 340 and the second reflecting target 350 are respectively a first corner bevel prism and a second corner bevel prism. For example... Figure 7 As shown, temperature changes may cause local deformation of the portion of the measured end face located in the reflective target mounting area, resulting in linear and / or angular displacement of the reflective target relative to its initial position. Changes in the position or attitude of the reflective target alter the measurement optical path of the absolute ranging module 300, causing the absolute distance data obtained by the absolute ranging module 300 to contain measurement errors caused by the local deformation of the reflective target mounting area.

[0090] In this step, the first local deformation δ of the first corner cube prism mounting area is extracted from the full-field displacement data of the first end face 710 output by the first digital speckle interferometry measurement unit 100. zc1 From the full-field displacement data of the second end face 720 output by the second digital speckle interferometry unit 200, the second local deformation δ of the second corner cube prism mounting area is extracted. zc2 .

[0091] S400, based on the first local deformation δ zc1 Second local deformation δzc2 For absolute distance data L abs Make corrections to obtain the corrected absolute distance L. corr .

[0092] In this embodiment, the first local deformation amount δ zc1 Second local deformation δ zc2 Converted into the corresponding local deformation relative to the absolute distance data L abs The resulting error components are corrected according to the following formula: L corr = L abs - (δ zc1 + δ zc2 ) Among them, L corr This represents the absolute distance between the corrected first end face 710 and the second end face 720. The first local deformation amount δ zc1 Second local deformation δ zc2 Using its absolute distance data L abs The positive or negative sign corresponds to the direction of influence.

[0093] S500, based on the corrected absolute distance L corr Given the initial absolute distance L0, determine the change in absolute distance ΔL between the first end face 710 and the second end face 720. corr : ΔL corr = L corr - L0.

[0094] Based on the absolute distance change ΔL corr The axial relative displacement between the first end face 710 and the second end face 720, determined using the first and second full-field displacement data, is calibrated to obtain the calibrated axial relative displacement Δz. calib .

[0095] In this embodiment, the absolute distance change ΔL corr As the calibrated axial relative displacement, that is: Δz calib =ΔL corr .

[0096] S600, based on the first full-field displacement data and the second full-field displacement data, determine the two lateral relative displacements and three angular displacements between the first end face 710 and the second end face 720, and compare the two lateral relative displacements and three angular displacements with the calibrated axial relative displacement Δz. calib By combining them, a six-degree-of-freedom relative pose between the first end face 710 and the second end face 720 is obtained.

[0097] Specifically, the relative displacements in the X and Y directions, as well as the three angular displacements around the X, Y, and Z directions in the fused six-degree-of-freedom relative pose, are relative displacements determined based on the measurement results of the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200. The relative displacement in the Z direction is the axial relative displacement Δz calibrated using dual-comb absolute distance data. calib .

[0098] The above steps can be repeated at different predetermined measurement nodes to obtain the relationship between the six-degree-of-freedom relative pose of the first end face 710 and the second end face 720 as a function of temperature and / or time.

[0099] like Figure 8 As shown, the data analysis software can display the six-degree-of-freedom relative pose measurement results obtained after data fusion. These measurement results are obtained after the aforementioned local deformation correction and axial displacement calibration. Figure 8 The horizontal axis represents the measurement time. The measurement results include three linear displacement components Lx, Ly, and Lz along the X, Y, and Z directions, as well as three angular displacement components pitch, yaw, and roll around the X, Y, and Z directions. Figure 8 The temperature of the tested spatial structure 700 is also displayed simultaneously to correlate the changes in the six-degree-of-freedom relative pose with the temperature state at the corresponding measurement time. During the test, the temperature curve remains basically stable during the measurement period, and the three linear displacement components and three angular displacement components can be continuously output with the measurement time, thus characterizing the position and attitude changes between the two end faces of the tested spatial structure 700 during the thermal deformation test.

[0100] In some embodiments, the control and processing unit 600 performs rigid body motion fitting on the full-field displacement data of each end face based on the end face full-field displacement distribution obtained by the first digital speckle interferometry unit 100 and the second digital speckle interferometry unit 200, decouples the six-degree-of-freedom pose change of the corresponding end face from the full-field displacement data, and determines the displacement that deviates from the rigid body motion fitting result as the local surface deformation of the end face. This allows for the differentiation between the overall rigid body motion and the local surface deformation of the end face while measuring the end face pose change, thereby reducing the influence of the local surface deformation on the six-degree-of-freedom pose measurement result.

[0101] Digital speckle interferometry (DIA) is a full-field, incremental measurement method capable of obtaining the full-field displacement distribution and six-degree-of-freedom pose changes of the end face with high resolution. However, it may accumulate errors during long-term, continuous measurements. An absolute ranging module provides absolute distance information and offers long-term stability. The measurement device provided in this application fuses DIA data and dual-comb absolute ranging data. It uses DIA to monitor local deformation in the cornerstone prism mounting area and correct the dual-comb absolute ranging results. Simultaneously, it uses the corrected absolute distance to calibrate the axial incremental displacement obtained from DIA. This approach retains the full-field and dynamic measurement capabilities of DIA while also providing an absolute distance reference, achieving complementarity between absolute distance measurement and incremental measurement.

[0102] Specifically, when the mounting area of ​​the cornerstone prism undergoes local deformation due to temperature changes, it may cause changes in the position and orientation of the cornerstone prism, thereby altering the measurement optical path of the dual-comb absolute ranging module. This application utilizes full-field displacement data obtained through digital speckle interferometry to extract the local deformation of the cornerstone prism mounting area and corrects the dual-comb absolute ranging results at each measurement node. This reduces the impact of local deformation of the cornerstone prism mounting area and the resulting changes in the target mirror's position and orientation on the absolute ranging results, thereby minimizing measurement errors caused by multi-degree-of-freedom motion crosstalk.

[0103] In the embodiment of thermal deformation measurement of a spacecraft deployable arm with a length of approximately 10m, the above-mentioned system layout and data fusion method are adopted, and the displacement measurement accuracy is better than 3μm and the angle measurement resolution is better than 0.001°, which can meet the micron-level thermal deformation measurement requirements of large-scale deployable arms in vacuum high and low temperature environments.

[0104] Compared to existing technologies, this application acquires full-field displacement data of the two end faces of the measured spatial structure using a digital speckle interferometry unit. This allows for the determination of the six-degree-of-freedom pose changes and local surface deformations of the end faces, thereby reducing the impact of local surface deformations on the pose measurement results. Simultaneously, by extracting the local deformation of the reflective target mounting area from the full-field displacement data and using this local deformation to correct the absolute ranging results, the ranging error introduced by thermal deformation of the reflective target mounting area can be reduced. Furthermore, the axial incremental displacement obtained by digital speckle interferometry is calibrated using the corrected absolute ranging results, achieving complementarity between full-field incremental measurement and absolute distance measurement. This is beneficial for improving the accuracy and stability of six-degree-of-freedom thermal deformation measurement of large-scale spatial structures under vacuum high and low temperature environments.

[0105] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatuses described in the embodiments, since they correspond to the methods described in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0106] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A large-scale spatial structure thermal deformation measurement device, used to measure the six-degree-of-freedom relative pose between the first end face and the second end face of the measured spatial structure, characterized in that, include: An environmental simulation container has an internal space for accommodating the measured spatial structure. The environmental simulation container has a first side and a second side that are arranged opposite to each other. The first side has a first optical window that is opposite to the first end face, and the second side has a second optical window that is opposite to the second end face. The first digital speckle interferometry measurement unit is disposed outside the first optical window and is used to acquire the first full-field displacement data of the first end face through the first optical window. The second digital speckle interferometry measurement unit is disposed outside the second optical window and is used to acquire the second full-field displacement data of the second end face through the second optical window; An absolute distance measurement module is used to obtain absolute distance data corresponding to the distance between the first end face and the second end face; and The control and processing unit is used to obtain the six-degree-of-freedom relative pose between the first end face and the second end face based on the first full-field displacement data, the second full-field displacement data, and the absolute distance data.

2. The large-scale spatial structure thermal deformation measurement device according to claim 1, characterized in that, The absolute ranging module includes: The first absolute ranging unit and the second absolute ranging unit are disposed on the first side; A first reflective target is provided on the first end face, and the mounting area of ​​the first reflective target is located within the measurement range of the first digital speckle interferometry unit. A second reflective target is provided on the second end face, and the mounting area of ​​the second reflective target is located within the measurement range of the second digital speckle interferometry unit. The first absolute ranging unit is used to measure the absolute distance to the first reflective target, and the second absolute ranging unit is used to measure the absolute distance to the second reflective target, so as to obtain absolute distance data corresponding to the distance between the first end face and the second end face.

3. The large-scale spatial structure thermal deformation measurement device according to claim 2, characterized in that, The absolute ranging module is a dual-comb absolute ranging module; The first reflective target uses a first corner bevel prism, and the second reflective target uses a second corner bevel prism. The first corner bevel prism and the second corner bevel prism are respectively disposed at the edge positions of the first end face and the second end face. The reflective surfaces of the first corner bevel prism and the second corner bevel prism both face towards the side where the light source of the dual-comb absolute ranging module is located, and the installation positions of the first corner bevel prism and the second corner bevel prism on the corresponding end faces are staggered from each other.

4. The large-scale spatial structure thermal deformation measurement device according to claim 2, characterized in that, The control and processing unit is connected to the first digital speckle interferometry measurement unit, the second digital speckle interferometry measurement unit, and the absolute ranging module, respectively. The control and processing unit is used to determine the first local deformation data of the installation area of ​​the first reflective target and the second local deformation data of the installation area of ​​the second reflective target based on the first full-field displacement data and the second full-field displacement data, respectively. And for correcting the absolute distance data based on the first local deformation data and the second local deformation data; And to calibrate the axial relative displacement between the first end face and the second end face based on the corrected absolute distance data, and to combine the calibrated axial relative displacement with two lateral relative displacements and three angular displacements determined based on the first full-field displacement data and the second full-field displacement data to obtain a six-degree-of-freedom relative pose between the first end face and the second end face.

5. The large-scale spatial structure thermal deformation measurement device according to claim 1, characterized in that, The environmental simulation container is a vacuum high and low temperature container, used to create a vacuum high and low temperature alternating environment within the containment space.

6. The large-scale spatial structure thermal deformation measurement device according to claim 1, characterized in that, The first optical window includes a light-transmitting area through which the measurement light of the first digital speckle interferometry measurement unit and the measurement light of the absolute ranging module pass; The second optical window includes a plurality of light-transmitting areas spaced apart, each of which corresponds to a corresponding measurement optical path of the second digital speckle interferometry unit.

7. The large-scale spatial structure thermal deformation measurement device according to claim 1, characterized in that, It also includes an air-floating vibration isolation platform, wherein the environmental simulation container, the first digital speckle interferometry measurement unit, the second digital speckle interferometry measurement unit, and the absolute ranging module are disposed on the air-floating vibration isolation platform.

8. A method for measuring the thermal deformation of large-scale spatial structures, characterized in that, include: Before thermal deformation occurs in the tested spatial structure, the initial absolute distance between the first end face and the second end face of the tested spatial structure is obtained. During the thermal deformation of the measured spatial structure, the first full-field displacement data of the first end face is obtained by the first digital speckle interferometry measurement unit, the second full-field displacement data of the second end face is obtained by the second digital speckle interferometry measurement unit, and the current absolute distance data corresponding to the distance between the first end face and the second end face is obtained by the absolute distance measurement module. Based on the installation position of the first reflective target on the first end face, the first local deformation data of the installation area of ​​the first reflective target is extracted from the first full-field displacement data; based on the installation position of the second reflective target on the second end face, the second local deformation data of the installation area of ​​the second reflective target is extracted from the second full-field displacement data. The current absolute distance data is corrected based on the first local deformation data and the second local deformation data; Based on the change in the corrected current absolute distance data relative to the initial absolute distance, calibrate the axial relative displacement between the first end face and the second end face determined based on the first full-field displacement data and the second full-field displacement data; as well as The calibrated axial relative displacement is combined with two lateral relative displacements and three angular displacements determined based on the first full-field displacement data and the second full-field displacement data to obtain the six-degree-of-freedom relative pose between the first end face and the second end face.

9. The method for measuring the thermal deformation of large-scale spatial structures according to claim 8, characterized in that, The measured spatial structure is housed within a vacuum high-low temperature container, and the measurement method further includes: The measured spatial structure is heated and / or cooled according to a predetermined temperature change process; At the measurement node where the measured spatial structure reaches a predetermined temperature, the first digital speckle interferometry measurement unit and the second digital speckle interferometry measurement unit are synchronously triggered to perform full-field displacement measurement, and the current absolute distance data output by the absolute ranging module at the measurement node is obtained, so that the first full-field displacement data, the second full-field displacement data and the current absolute distance data correspond to each other in time.

10. The method for measuring the thermal deformation of large-scale spatial structures according to claim 8, characterized in that, The current absolute distance data shall be corrected according to the following formula: L corr = L abs - (d zc1 + d zc2 ); Among them, L corr L is the corrected absolute distance between the first and second end faces. abs For the absolute distance data, δ zc1 Let δ be the first local deformation. zc2 This is the second local deformation amount; The change in the corrected current absolute distance data relative to the initial absolute distance is determined according to the following formula: ΔL corr = L corr - L0; Where, ΔL corr L0 represents the change in absolute distance, and L0 represents the initial absolute distance.

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