Three-dimensional curved surface two-stage reconstruction measurement method, measurement system and processing and manufacturing system

Abstract

The invention belongs to the related technical field of industrial measurement, and discloses a three-dimensional curved surface two-stage reconstruction measurement method, measurement system and processing and manufacturing system.The measurement method comprises the steps that a rough measurement model of a workpiece to be measured is obtained based on design or scanning, and rough measurement point cloud data of the rough measurement model in a workpiece coordinate system established on a clamp are obtained; determining a target accurate measurement area on the surface of the to-be-measured workpiece, and performing accurate measurement path planning on the target accurate measurement area; according to the planned accurate measurement path, performing secondary accurate measurement on the to-be-measured workpiece by using laser measurement to obtain accurate measurement point cloud data; and correcting the rough measurement point cloud data by using the fine measurement point cloud data to realize reconstruction measurement of the surface point cloud of the to-be-measured workpiece. According to the method, a two-stage reconstruction method is adopted, the target object is subjected to coarse reconstruction and fine reconstruction in sequence, only a measurement track with low density needs to be operated in the fine reconstruction process, therefore, the measurement efficiency can be improved, meanwhile, coarse measurement data can be corrected through fine measurement, and the measurement accuracy is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of industrial measurement technology, and more specifically, relates to a two-level reconstruction measurement method, measurement system and processing and manufacturing system for three-dimensional curved surfaces. Background Technology

[0002] The development of curved surface electronics technology has enabled more integrated and lightweight electronic products, showing great application potential in fields such as conformal antennas, wearable electronics, electronic skin, and smart skin for aircraft. However, this also presents challenges to conformal manufacturing technology for curved surfaces. Conformal printing technology can directly manufacture circuits on arbitrary curved surfaces, and the application of robots in this field expands the manufacturing area and the objects that can be manufactured, while also bringing challenges in terms of processing accuracy. During conformal printing using robots, when the workpiece model is not accurately established or the workpiece coordinate system is inaccurate, there is a deviation between the robot's planned trajectory and the actual running trajectory. This results in an inconsistent distance between the printing nozzle and the curved substrate, affecting the consistency of the printed circuit and even causing collisions or interference. Therefore, a method and equipment are urgently needed to solve the measurement and positioning problems in the large-area curved surface conformal printing process.

[0003] Currently, non-contact measurement is commonly used in the field of large-area curved surface measurement to achieve on-machine measurement. Non-contact measurement acquires measurement point information of the object being measured without contacting its surface. It generally relies on optical and electromagnetic technologies as its measurement principle, with common methods including structured light measurement and laser measurement. Structured light measurement enables large-area, rapid measurements, but its accuracy is lower for surfaces with high transparency or texture. Spectral confocal laser measurement is less affected by the refractive index and morphology of the surface, but its measurement range is limited and its efficiency is low. Therefore, current large-area curved surface measurement technologies face the challenge of balancing measurement efficiency and accuracy, thus limiting the further promotion of large-area curved surface electronic conformal manufacturing technology. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a two-level reconstruction measurement method, measurement system, and manufacturing system for three-dimensional curved surfaces, which solves the problem of difficulty in balancing measurement efficiency and accuracy in current large-area curved surface measurement technologies.

[0005] To achieve the above objectives, according to a first aspect of the present invention, a two-level reconstruction measurement method for three-dimensional curved surfaces is provided, comprising: S1. Based on the design or scanning, obtain the surface model of the workpiece to be measured as the rough measurement model, and obtain the rough measurement point cloud data of the rough measurement model in the workpiece coordinate system established on the fixture according to the assembly relationship between the workpiece to be measured and the fixture on the machining platform. S2, determine the target precision measurement area on the surface of the workpiece to be measured according to the processing requirements of the workpiece to be measured, and plan the precision measurement path for the target precision measurement area; S3, according to the planned precision measurement path, use laser measurement to perform secondary precision measurement on the workpiece to be measured, and obtain precision measurement point cloud data; S4 uses the fine point cloud data to correct the coarse point cloud data, thereby realizing the reconstruction measurement of the point cloud on the surface of the workpiece to be measured.

[0006] According to the two-level reconstruction measurement method for three-dimensional curved surfaces provided by the present invention, S1 specifically includes: Based on the design model or existing scanning model of the workpiece to be tested, the surface model of the workpiece to be tested is obtained as the rough measurement model. According to the assembly relationship between the workpiece to be tested and the fixture, and the positional relationship between the fixture and the workpiece coordinate system, the rough measurement point cloud data of the rough measurement model in the workpiece coordinate system is obtained. Alternatively, the workpiece to be measured can be placed on a machining platform, and a scanning instrument can be used to scan the workpiece and the fixture simultaneously to obtain the surface model of the workpiece as a rough measurement model. The rough measurement point cloud data of the rough measurement model in the workpiece coordinate system can be obtained according to the positional relationship between the fixture and the workpiece coordinate system.

[0007] According to the two-level reconstruction measurement method for three-dimensional curved surfaces provided by the present invention, the fine measurement path in S2 is spiral, zigzag, or serpentine. In S3, the precise point cloud data of the workpiece under test in the workpiece coordinate system is obtained based on the pre-calibrated positional relationship between the laser measurement position and the workpiece coordinate system.

[0008] According to the two-level reconstruction measurement method for three-dimensional curved surfaces provided by the present invention, S2 involves precise measurement path planning for the target precision measurement area, specifically including: For the parts of the target precision measurement area that have coarse measurement point cloud data, a precision measurement path point with a first density is planned. The first density is determined according to the curvature of different positions of the surface, so that the surface bow height between adjacent path points is less than a first preset threshold. For areas in the target precision measurement area where coarse measurement point cloud data is missing, plan precision measurement path points with a second density; where the second density is higher than the first density.

[0009] According to the two-level reconstruction measurement method for three-dimensional curved surfaces provided by the present invention, step S4 involves correcting the coarse point cloud data using fine point cloud data, specifically including: The surface is fitted using the fine measurement point cloud data. The deviation of any coarse measurement point cloud in the coarse measurement point cloud data from the fitted surface is calculated. For coarse measurement point clouds whose deviation exceeds the second preset threshold, local transformation correction is performed along the normal of the fitted surface. For the missing parts of the coarse point cloud data after local transformation correction, the fine point cloud data is used to fill in the missing parts. According to the two-level reconstruction measurement method for three-dimensional surfaces provided by the present invention, step S4 further includes the following before performing local transformation correction: The fine measurement point cloud data is fixed, and the coarse measurement point cloud data is registered with the fine measurement point cloud data to correct the coarse measurement point cloud data as a whole.

[0010] According to a second aspect of the present invention, a two-level reconstruction measurement system for a three-dimensional curved surface is provided, comprising a processing platform, a rotating platform, a fixture, a gantry motion assembly, and a laser measurement end. The rotating platform is rotatably mounted on the processing platform, the fixture is fixedly mounted on the rotating platform, the gantry motion assembly is mounted on the processing platform, and the laser measurement end is connected to the gantry motion assembly. The system also includes a controller connected to the rotating platform, the gantry motion assembly, and the laser measurement end, respectively. The controller is used to control each component to implement the two-level reconstruction measurement method for a three-dimensional curved surface as described above.

[0011] According to the three-dimensional curved surface two-level reconstruction measurement system provided by the present invention, the gantry motion assembly includes an X-axis linear module and a Z-axis linear module. The two X-axis linear modules are arranged parallel to each other on both sides of the rotating platform. A Z-axis linear module is vertically connected to the X-axis sliding seat of each X-axis linear module. A mounting beam is connected between the Z-axis sliding seats of the two Z-axis linear modules. The laser measurement end is connected to the mounting beam.

[0012] According to the three-dimensional curved surface two-level reconstruction measurement system provided by the present invention, a transverse connecting rod is also connected between the two Z-axis linear modules; A Z-axis verticality adjustment component is also connected between the Z-axis linear module and the X-axis sliding seat. The Z-axis verticality adjustment component includes a ball joint connecting rod, a ball joint screw, and a ball joint threaded sleeve connected in sequence. The laser measurement end angle is adjustable and can be translatably connected to the mounting beam between the two Z-axis linear modules; The fixture is equipped with a positioning structure that matches the workpiece to be measured.

[0013] According to a third aspect of the present invention, a three-dimensional surface machining and manufacturing system is provided, including the three-dimensional surface two-level reconstruction measurement system described in any of the above claims, and further including a machining execution system disposed beside the machining platform.

[0014] Overall, compared with the prior art, the three-dimensional surface two-level reconstruction measurement method, measurement system, and processing and manufacturing system provided by the present invention offer the following advantages: 1. By adopting a two-level reconstruction method, the target object is reconstructed in a coarse and fine manner in sequence. In the fine reconstruction process, only a low-density measurement trajectory needs to be run, which can improve the measurement efficiency. At the same time, the fine measurement can correct the coarse measurement data, thereby ensuring the measurement accuracy and achieving a balance between efficiency and accuracy, thus expanding the application market. 2. The coarse point cloud data is corrected by using the fine point cloud data. On the one hand, the coarse point cloud data is corrected and completed. On the other hand, by registering the coarse point cloud data with the fine point cloud data, the workpiece coordinate system can be positioned and corrected, thereby further improving the measurement accuracy. 3. The measurement system can achieve large-area measurement through the combination structure of the rotating platform and the gantry frame. The precision measurement process is carried out using the gantry precision measurement platform. Both the gantry precision measurement platform and the positioning fixture are built on the machining platform. The positional relationship between the gantry precision measurement platform and the workpiece coordinate system can be determined in advance. This method uses low-density trajectory to improve the precision reconstruction efficiency, realizes large-area measurement using the gantry measurement platform, and improves positioning accuracy through the unification of the coordinate system. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the three-dimensional surface two-level reconstruction measurement system provided by the present invention.

[0016] Figure 2 This is a schematic diagram of the installation of the laser measurement end provided by the present invention.

[0017] Figure 3 This is a schematic diagram of the establishment of various coordinate systems provided by the present invention.

[0018] Figure 4 This is a schematic diagram of the workpiece coordinate system establishment provided by the present invention.

[0019] Figure 5 This is a flowchart illustrating the two-level reconstruction measurement method for three-dimensional curved surfaces provided by the present invention.

[0020] Figure 6 This is a positioning diagram of the workpiece provided by the present invention when it has a rough measurement model.

[0021] Figure 7 This is a schematic diagram of coarse measurement and positioning when the workpiece does not have a coarse measurement model, as provided by the present invention.

[0022] Figure 8 This is an example of a workpiece point cloud after two-level reconstruction provided by the present invention.

[0023] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-Z-axis of the measuring platform; 2-Laser measuring end; 3-Z-axis verticality adjustment component; 4-X-axis of the measuring platform; 5-Turntable of the measuring platform; 6-Marble vibration damping platform; 8-Coarse measurement scanner; 101-Transverse connecting rod; 102-Z-axis module driver; 103-Z-axis linear module; 104-Hanging beam; 105-Z-axis grating ruler; 201-Horizontal mounting plate of the slide table; 202-Vertical mounting plate of the slide table; 203-End hand-cranked turntable; 204-End measuring angle turntable; 205-Probe clamping fixture; 206-Spectral confocal laser probe; 301-Spherical hinge connection Connecting rod, 302-spherical hinge screw, 303-spherical hinge threaded sleeve; 401-X-axis sliding seat, 402-X-axis linear module, 403-X-axis grating ruler; 501-rotary platform, 502-positioning fixture, 503-spherical workpiece, 504-semi-cylindrical workpiece, 505-conical workpiece, 506-wing workpiece; 701-probe focal coordinate system, 702-gantry beam coordinate system, 703-workpiece coordinate system, 704-turntable center coordinate system, 705-robot 1 base coordinate system, 706-robot 2 base coordinate system, 707-robot 3 base coordinate system. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Please see Figure 1 and Figure 5 This embodiment provides a two-level reconstruction measurement method for three-dimensional surfaces, which includes: S1. Based on the design or scanning, obtain the surface model of the workpiece to be measured as the rough measurement model, and obtain the rough measurement point cloud data of the rough measurement model in the workpiece coordinate system established on the fixture according to the assembly relationship between the workpiece to be measured and the fixture on the machining platform. S2, determine the target precision measurement area on the surface of the workpiece to be measured, i.e., the rough measurement model, according to the processing requirements of the workpiece to be measured, and plan the precision measurement path for the target precision measurement area. S3, according to the planned precision measurement path, use laser measurement to perform secondary precision measurement on the workpiece to be measured, and obtain precision measurement point cloud data; S4 uses the fine point cloud data to correct the coarse point cloud data, thereby realizing the reconstruction measurement of the point cloud on the surface of the workpiece to be measured.

[0026] This embodiment proposes a three-dimensional surface reconstruction measurement method that utilizes coarse measurement to guide fine measurement, aiming to achieve both high accuracy and high efficiency in measurement technology. Specifically, this embodiment first acquires a coarse measurement model of the workpiece to be measured, collecting coarse measurement point cloud data that constitutes the overall outline of the surface. By processing this coarse measurement point cloud data, a preliminary coarse measurement model of the target surface can be constructed. Based on this, a path for secondary fine measurement is planned, and secondary measurement is performed using laser fine measurement methods such as point laser measuring heads, thereby obtaining accurate measurement results. By using coarse measurement to guide fine measurement, the number of path points requiring fine measurement based on the coarse measurement can be greatly reduced, thus improving measurement efficiency. Simultaneously, fine measurement can correct and adjust the coarse measurement data, ensuring measurement accuracy and achieving a balance between efficiency and accuracy, thus expanding the application market.

[0027] In some embodiments, S1 specifically includes: Based on the design model or existing scanning model of the workpiece to be tested, the surface model of the workpiece to be tested is obtained as the rough measurement model. According to the assembly relationship between the workpiece to be tested and the fixture, and the positional relationship between the fixture and the workpiece coordinate system, the rough measurement point cloud data of the rough measurement model in the workpiece coordinate system is obtained. Alternatively, the workpiece to be measured can be placed on a machining platform, and a scanning instrument can be used to scan the workpiece and the fixture simultaneously to obtain the surface model of the workpiece as a rough measurement model. The rough measurement point cloud data of the rough measurement model in the workpiece coordinate system can be obtained according to the positional relationship between the fixture and the workpiece coordinate system.

[0028] In this embodiment, when the workpiece to be tested has a design model or an existing scanned model, the relative position of the workpiece and the fixture is determined by the assembly relationship between the workpiece and the fixture. When there is no design model or an existing scanned model, point cloud data can be obtained through online scanning. Standard features on the fixture are identified in the point cloud to establish a coordinate system for workpiece positioning. When the workpiece to be tested needs to obtain a rough measurement model through scanning, a rough measurement device can be used to obtain the rough measurement model. The rough measurement device can be a structured light camera or a 3D scanner.

[0029] Specifically, it can be first determined whether the workpiece to be measured has an existing coarse measurement model. If an existing coarse measurement model exists, it can be directly assembled with the standard features on the fixture, and the assembly fixture can be drawn in the modeling software according to the actual assembly relationship. In the 3D modeling software, the workpiece coordinate system on the fixture is used as the reference to establish the assembly of the workpiece and the positioning fixture. If no existing coarse measurement model exists, the workpiece can be placed at any position on the worktable, and the coarse measurement scanning instrument can be used to scan both the workpiece and the fixture model simultaneously. (Refer to...) Figure 7 A 3D scanner is used to scan the workpiece and the positioning fixture simultaneously to obtain point clouds. Then, the orthogonal plane features on the positioning fixture are identified in the point cloud processing software. The origin of the workpiece coordinate system can be set at the positioning feature position of the fixture, such as the intersection of orthogonal planes.

[0030] In some embodiments, the precision measurement path in S2 is spiral, zigzag, or serpentine; In S3, the precise point cloud data of the workpiece under test in the workpiece coordinate system is obtained based on the pre-calibrated positional relationship between the laser measurement position and the workpiece coordinate system.

[0031] S2 performs detailed survey path planning for the target detailed survey area, specifically including: For the parts of the target precision measurement area that have coarse measurement point cloud data, a precision measurement path point with a first density is planned. The first density is determined according to the curvature of different positions of the surface, so that the surface bow height between adjacent path points is less than a first preset threshold. For areas in the target precision measurement area where coarse measurement point cloud data is missing, a second density of precision measurement path points is planned; where the second density is higher than the first density. That is, a low-density precision measurement trajectory is planned overall, and only a low-density trajectory is set in locations where there are no missing or singular points in the coarse measurement model, while a high-density trajectory is planned in areas where there are missing points in the coarse measurement model to complete the point cloud.

[0032] In some embodiments, S4 uses fine-measured point cloud data to correct coarse-measured point cloud data, specifically including: A surface is fitted using the fine-measured point cloud data. The deviation of any coarse-measured point cloud from the coarse-measured point cloud data relative to the fitted surface is calculated. For coarse-measured point clouds whose deviation exceeds a second preset threshold, local transformation correction is performed along the normal direction of the fitted surface. The deviation of the coarse-measured point cloud from the fitted surface is the distance relative to the fitted surface in the normal direction. When the deviation exceeds the threshold range, local transformation correction can be performed on the coarse-measured point cloud using points on the fitted surface corresponding to the normal direction of the fitted surface. Alternatively, local transformation correction can be performed using the midpoint between the coarse-measured point cloud and the corresponding point on the fitted surface. The specific method is not limited. The surface fitted using the fine-measured point cloud data can be a NURBS surface. For the missing parts of the coarse point cloud data after local transformation correction, the fine point cloud data is used to fill in the missing parts. Then, redundant fine point cloud data can be deleted to form a high-precision and high-completeness point cloud with the corrected coarse point cloud data as the main component.

[0033] Furthermore, S4 also includes the following before performing local transformation correction: The precise point cloud data is fixed, and the coarse point cloud data is registered with it to correct the overall coarse point cloud data. The transformation matrix during registration can be calculated to transform the coarse point cloud as a whole, thereby correcting the workpiece coordinate system. The overall registration between point cloud data can be performed using point cloud registration algorithms, such as the Iterative Closest Point (ICP) algorithm or the Normal Distribution (NDT) algorithm, etc., without specific limitations.

[0034] Furthermore, in other embodiments, a two-level reconstruction measurement system for three-dimensional curved surfaces is also provided. This system includes a machining platform, a rotating platform, a fixture, a gantry motion assembly, and a laser measurement terminal. The rotating platform is rotatably mounted on the machining platform, the fixture is fixedly mounted on the rotating platform, the gantry motion assembly is mounted on the machining platform, and the laser measurement terminal is connected to the gantry motion assembly. The system also includes a controller connected to the rotating platform, the gantry motion assembly, and the laser measurement terminal, respectively. The controller is used to control each component to implement the two-level reconstruction measurement method for three-dimensional curved surfaces as described above.

[0035] Reference Figure 1 , Figure 2 and Figure 3 A three-dimensional curved surface two-level reconstruction measurement system includes a precision measurement platform, which includes a measurement platform Z-axis 1, a measurement platform X-axis 4, a laser measurement end 2, a measurement platform turntable 5, and a processing platform (e.g., a marble vibration damping platform 6). The measurement platform Z-axis 1 and the measurement platform X-axis 4 form a gantry motion assembly, specifically including a Z-axis module driver 102, a Z-axis linear module 103, a Z-axis grating ruler 105, an X-axis linear module 402, an X-axis grating ruler 403, a rotary platform 501, a marble vibration damping platform 6, a transverse connecting rod 101, a hanging crossbeam 104, a ball joint connecting rod 301, a ball joint screw 302, a ball joint threaded sleeve 303, an X-axis sliding seat 401, and a Z-axis sliding seat. The main body of the precision measurement platform consists of a rotating platform 501, a linear motion gantry, a marble vibration damping platform 6, and a laser measurement end 2 (e.g., a spectral confocal measurement end). The rotating platform 501 is connected to the positioning fixture 502 by bolts. When the rotating platform rotates, it can drive the positioning fixture 502 and the workpiece to be measured on it to rotate. Together with the linear motion gantry, it can achieve a full-range fine scan of the workpiece. At the same time, a rotating platform grating ruler is installed under the rotating platform 501 to accurately read the rotation angle and improve the motion accuracy.

[0036] The linear motion gantry, or gantry motion assembly, includes a Z-axis linear module 103 and an X-axis linear module 402. Their combined motion drives the scanning motion of the spectral confocal measurement end; wherein: Two X-axis linear modules 402 are arranged parallel to each other on both sides of the rotating platform 501. Each X-axis linear module 402 has a Z-axis linear module 103 vertically connected to its X-axis sliding seat 401. The upper end of the Z-axis linear module 103 is connected to the Z-axis module driver 102, and power lines, signal lines, etc. are laid between them. The lower end of the Z-axis linear module 103 is threadedly connected to the X-axis sliding seat 401. The X-axis sliding seat 401 is connected to the guide rail of the X-axis linear module 402, so that when the X-axis linear module 402 moves linearly, it can drive the X-axis sliding seat 401 and the Z-axis linear module 103 to move. The Z-axis linear module 103 has a self-locking function when the system is powered off, and can stay in its current position when the power is off, without sliding to the bottom. A mounting beam 104 is connected between the Z-axis sliding seats of the two Z-axis linear modules 103. The two ends of the Z-axis sliding seats and the mounting beam 104 can be connected by threads. The mounting beam 104 moves with the Z-axis linear module 103. The laser measurement end can be connected to the middle of the mounting beam 104 by threads. When the Z-axis linear module 103 moves up and down, it drives the measurement end to move in the Z-axis direction. A transverse connecting rod 101 is also connected between the two Z-axis linear modules 103; the top of a set of Z-axis linear modules 103 can be threaded to both ends of the transverse connecting rod 101 to limit the vibration of the Z-axis linear modules 103 during movement and to assist in the perpendicularity and parallelism between the leveling modules. A Z-axis verticality adjustment component 3 is also connected between the Z-axis linear module 103 and the X-axis sliding seat 401. Specifically, a ball joint connecting rod 301, a ball joint screw 302, and a ball joint threaded sleeve 303 are sequentially connected to the rear of the Z-axis linear module 103. The ball joint connecting rod 301 and the ball joint screw 302 are connected by a ball joint chain, and the ball joint screw 302 and the ball joint threaded sleeve 303 are threaded together. By adjusting the ball joint screw 302 to screw in and out of the ball joint connecting rod 301 and the ball joint threaded sleeve 303, the verticality and flatness limit of the Z-axis linear module 103 can be adjusted to ensure the straightness of the spectral confocal measurement end moving along the Z-axis.

[0037] One end of the Z-axis module driver 102 is used to connect to and control the Z-axis linear module 103, and the other end is connected to the host computer to receive motion commands. According to the host computer program commands, the driver controls the Z-axis linear module 103 to perform measurement path movement. The Z-axis grating ruler 105 is mounted on the inner side of the guide rail of the Z-axis linear module 103 to provide feedback on the movement of the Z-axis linear module 103 and improve the Z-axis movement accuracy. The Z-axis grating ruler 105 is connected to the encoding synchronization module and feeds back the pulse signal of the Z-axis movement to the encoding synchronization module. The X-axis linear module 402 is connected to the marble vibration damping platform 6 by threads, and the slider of the X-axis linear module 402 is connected to the X-axis sliding seat 401 by threads; the upper end of the X-axis sliding seat 401 is connected to the Z-axis linear module 103 and the ball joint threaded sleeve 303 respectively. A set of X-axis sliding seats 401 can be connected to limit the jitter of the X-axis linear module 402 during movement and assist in the parallelism between the leveling modules, ensuring the straightness of the spectral confocal measurement end along the X-axis; the X-axis sliding seat 401 is connected to the ball joint threaded sleeve 303, and the ball joint screw 302 can adjust the perpendicularity between the Z-axis linear module 103 and the X-axis linear module 402 based on the X-axis linear module 402; the two ends of the Z-axis perpendicularity adjustment component 3 can be rotatably connected to the Z-axis linear module 103 and the X-axis sliding seat 401 respectively.

[0038] The X-axis grating ruler 403 is mounted on the inner side of the guide rail of the X-axis linear module 402 to provide feedback on the motion of the X-axis linear module 402 and improve the X-axis motion accuracy. The X-axis grating ruler 403 is connected to the encoding synchronization module, which feeds back the pulse signal of the X-axis motion to the encoding synchronization module. The encoding synchronization module is used to control the transmission of the measurement signal of the laser measurement end 2 according to the position information fed back by the grating ruler. When it reaches the preset path point, it can synchronously acquire the laser measurement signal. The linear module can be a lead screw module, a slide table, or other linear displacement structure, and the specific type is not limited.

[0039] refer to Figure 2 The spectral confocal measurement end includes a horizontal sliding plate 201, a vertical sliding plate 202, a hand-cranked end turntable 203, an end-measuring angle turntable 204, a probe clamping fixture 205, and a spectral confocal laser probe 206, wherein: One end of the horizontal mounting plate 201 of the slide table is connected to the mounting beam 104 by a thread, and the other end is connected to the end hand-cranked turntable 203 by a thread; the upper end of the end hand-cranked turntable 203 is connected to the vertical mounting plate 202 of the slide table, and the other end of the vertical mounting plate 202 of the slide table is connected to the end measuring angle turntable 204. The end measuring angle turntable 204 is connected to the probe clamping fixture 205, which clamps and holds the spectral confocal laser probe 206. The end-effector hand-cranked turntable 203 integrates a linear translation mechanism. The vertical mounting plate 202 of the slide table can be connected to the slider of the translation mechanism, and the translation amount can be controlled by the end-effector hand-cranked turntable 203. The end-effector hand-cranked turntable 203 can simultaneously adjust the rotation amount of the end-effector measuring angle turntable 204. That is, by adjusting the rotation amount and the translation amount, the end-effector hand-cranked turntable 203 can ensure that the laser probe is located at the center of the mounting beam 104 and that the laser head is at a suitable angle, ensuring the accuracy of the measurement data. The end-effector measuring angle turntable 204 can drive the spectral confocal laser probe 206 to rotate, adjusting the measurement angle for different measurement environments and workpieces, and comprehensively and accurately measuring the workpiece. In other words, the laser measuring end 2 has an adjustable angle and can be translated between the two Z-axis linear modules 103 and connected to the mounting beam 104.

[0040] Furthermore, in other embodiments, a three-dimensional surface machining and manufacturing system is also provided. The machining and manufacturing system includes the three-dimensional surface two-level reconstruction measurement system described in any of the above embodiments, and also includes a machining execution system located beside the machining platform.

[0041] For example, a two-level reconstruction measurement system for a 3D curved surface can be integrated into a large-area conformal printing platform for a robot, and a precision measurement platform can be integrated into the conformal printing platform for the robot. The machining execution system can be a conformal printing system for the curved surface (e.g., a robot arm structure plus an end effector structure). There can be at least one machining execution system, corresponding to at least one process step in the manufacturing process; see reference. Figure 3 A coordinate system is established with the turntable center coordinate system 704 as the reference. The probe focus coordinate system 701 is located at the focal point of the spectral confocal probe. The gantry beam coordinate system 702 is located at any position on the gantry mounting beam 104. The workpiece coordinate system 703 is located at the intersection of the three orthogonal planes of the positioning fixture 502. The turntable center coordinate system 704 is located at the center of the upper surface of the rotating platform. The robot 1 base coordinate system 705 is located at the intersection of the extension lines of the "1" axis and the "2" axis of robot 1. The robot 2 base coordinate system 706 is located at the intersection of the extension lines of the "1" axis and the "2" axis of robot 2. The robot 3 base coordinate system 707 is located at the intersection of the extension lines of the "1" axis and the "2" axis of the three robots 3. Preferably, before establishing the workpiece coordinate system 703, calibration equipment such as a laser tracker can be used to calibrate the probe focal coordinate system 701, the gantry beam coordinate system 702, and the coordinate systems of each robot base to obtain a unified coordinate system transformation relationship based on the workpiece coordinate system. The workpiece coordinate system is located on the fixture and can be calibrated synchronously when the robot and the measurement system coordinate systems are calibrated, or it can be established by using the cone tip on the end of the robot or a laser displacement sensor to identify the geometric features on the fixture. refer to Figure 4The workpiece coordinate system 703 can be established by recognizing the right-angled side features on the fixture using a laser displacement sensor installed at the robot's end effector. The coordinates of the robot's end effector when it moves from its initial position to the intersection point of the three orthogonal planes of the positioning fixture 502, which is the origin of the workpiece coordinate system 703, are expressed in the robot programming system as a transformation matrix based on the robot coordinate system 706. After the workpiece coordinate system is calibrated, it only needs to be periodically recalibrated. Its coordinates do not change when the workpiece is changed, and all subsequent trajectory planning and point cloud processing steps are based on this coordinate system.

[0042] Furthermore, the precision measurement platform can synchronously read the motion information of the spectral confocal laser probe and the grating ruler. The encoding synchronization unit monitors the synchronization pulse signal of the confocal probe in real time based on the interrupt method. After detecting the pulse signal fed back by the probe, the synchronization unit reads the motion value fed back by the grating ruler of each axis. The motion value, i.e., the linear motion distance and rotation angle, is matched with the corresponding probe feedback reading. That is, the high-precision measurement system motion information and probe ranging information at the corresponding moment are registered through the synchronization signal. The motion information fed back by the grating ruler and the ranging information fed back by the probe are both TTL level signals, and there is a corresponding time synchronization relationship between the synchronization signal and the probe ranging information. The synchronized pulse data, i.e., the X-axis motion, Z-axis motion, rotation of the rotating platform, and probe ranging, are input to the data processing module, and high-precision three-dimensional point cloud data are obtained through coordinate transformation.

[0043] Furthermore, the fixture is equipped with a positioning structure that matches the workpiece to be measured. (Refer to...) Figure 6 The positioning fixture 502 has features such as orthogonal planes or conical surfaces, enabling stable assembly relationships between spherical workpieces 503, semi-cylindrical workpieces 504, conical workpieces 505, wing workpieces 506, etc., and the workpieces' planes, cylindrical surfaces, spherical surfaces, straight edges, etc., and ensuring a precise relative positional relationship after assembly. (Reference) Figure 7 The two-level reconstruction measurement system for three-dimensional curved surfaces also includes a coarse scanner 8, used to scan the workpiece to be measured to obtain a coarse measurement model when needed. (Refer to...) Figure 8 The above-mentioned two-level reconstruction method for three-dimensional curved surfaces has achieved high-precision and high-completeness point cloud reconstruction of conical workpieces.

[0044] This embodiment addresses the need for high-precision measurement and reconstruction of large-area complex curved surfaces in robotic conformal printing by providing a two-level reconstruction measurement method and system for three-dimensional curved surfaces. This method and system utilizes the high-precision structure of the fixture on the worktable to establish the workpiece coordinate system for the entire machining system, ensuring the workpiece coordinate system is in a fixed position. This eliminates the need to modify the workpiece coordinate system in the robot controller when changing workpieces, avoiding deviations caused by the workpiece coordinate system and improving machining efficiency. A low-precision model of the workpiece based on the workpiece coordinate system is acquired using a 3D scanner. The coarse measurement process can be performed offline or online. Then, a high-precision measurement platform with a shared coordinate system with the robot runs a low-density fine measurement trajectory to acquire point cloud data of key feature positions of the workpiece. This data is used to correct and complete the workpiece position coordinates and contour, solving the problems of low measurement accuracy and local measurement defects associated with handheld scanners, and improving the precision measurement efficiency in the traditional two-level surface reconstruction process. The measurement platform achieves large-range measurement through a combination of a rotary axis and a gantry structure, and the feed amount of each axis is small during the measurement process, avoiding measurement errors caused by mechanical vibration.

[0045] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A three-dimensional curved surface two-stage reconstruction measurement method, characterized in that, The method comprises the following steps: S1, obtaining a surface model of the workpiece to be measured as a rough measurement model based on design or scanning, and obtaining rough measurement point cloud data of the rough measurement model in the workpiece coordinate system established on the fixture according to the assembly relationship between the workpiece to be measured and the fixture on the machining platform; S2, determining a target precision measurement area of the surface of the workpiece to be measured according to the machining requirement of the workpiece to be measured, and planning a precision measurement path for the target precision measurement area; S3, performing secondary precision measurement on the workpiece to be measured by laser measurement according to the planned precision measurement path, and obtaining precision measurement point cloud data; S4, correcting the rough measurement point cloud data by using the precision measurement point cloud data to realize the reconstruction measurement of the surface point cloud of the workpiece to be measured.

2. The three-dimensional surface two-stage reconstruction measurement method of claim 1, wherein, S1 specifically comprises: obtaining a surface model of the workpiece to be measured as a rough measurement model based on the design model or the existing scanning model of the workpiece to be measured, and obtaining rough measurement point cloud data of the rough measurement model in the workpiece coordinate system according to the assembly relationship between the workpiece to be measured and the fixture and the positional relationship between the fixture and the workpiece coordinate system; or, placing the workpiece to be measured on the machining platform, and simultaneously scanning the workpiece to be measured and the fixture by using a scanning instrument to obtain a surface model of the workpiece to be measured as a rough measurement model, and obtaining rough measurement point cloud data of the rough measurement model in the workpiece coordinate system according to the positional relationship between the fixture and the workpiece coordinate system.

3. The three-dimensional surface two-stage reconstruction measurement method of claim 1, wherein, The precision measurement path in S2 is spiral, Hui-shaped or snake-shaped; In S3, the positional relationship between the laser measurement position and the workpiece coordinate system is obtained by pre-calibration, and the precision measurement point cloud data of the workpiece to be measured in the workpiece coordinate system is obtained.

4. The three-dimensional surface two-stage reconstruction measurement method of claim 1, wherein, In S2, the target precision measurement area is planned for precision measurement path, specifically comprising: for the part of the target precision measurement area where the rough measurement point cloud data exists, a first density of precision measurement path points is planned, the first density is determined according to the curvature of the surface at different positions, so that the surface arch height between adjacent path points is less than a first preset threshold; for the part of the target precision measurement area where the rough measurement point cloud data is missing, a second density of precision measurement path points is planned; wherein the second density is higher than the first density.

5. The three-dimensional surface two-stage reconstruction measurement method according to any one of claims 1-4, characterized in that, In S4, the rough measurement point cloud data is corrected by using the precision measurement point cloud data, specifically comprising: fitting a surface by using the precision measurement point cloud data, calculating the deviation degree of any rough measurement point cloud in the rough measurement point cloud data relative to the fitted surface, and correcting the rough measurement point cloud by local transformation along the normal direction of the fitted surface for the rough measurement point cloud whose deviation degree exceeds a second preset threshold; for the missing part of the rough measurement point cloud data after local transformation correction, the missing part is filled by using the precision measurement point cloud data.

6. The three-dimensional surface two-stage reconstruction measurement method of claim 5, wherein, In S4, before local transformation correction, it further comprises: fixing the precision measurement point cloud data, aligning the rough measurement point cloud data as a whole with the precision measurement point cloud data, and correcting the rough measurement point cloud data as a whole.

7. A three-dimensional curved surface two-stage reconstruction measurement system, characterized in that, The machining platform, the rotating platform, the fixture, the gantry motion assembly and the laser measurement end, the rotating platform is rotatably installed on the machining platform, the fixture is fixedly installed on the rotating platform, the gantry motion assembly is installed on the machining platform, and the laser measurement end is connected to the gantry motion assembly; further comprising a controller connected with the rotating platform, the gantry motion assembly and the laser measurement end respectively, the controller is used for controlling each part to realize the three-dimensional curved surface two-stage reconstruction measurement method in any one of claims 1-6.

8. The three-dimensional surface two-stage reconstruction measurement system of claim 7, wherein, The gantry motion assembly comprises X-axis linear modules and Z-axis linear modules, two X-axis linear modules are arranged in parallel on two sides of the rotating platform, one Z-axis linear module is vertically connected to the X-axis sliding seat of each X-axis linear module, a hanging cross beam is connected between the Z-axis sliding seats of the two Z-axis linear modules, and the laser measurement end is connected to the hanging cross beam.

9. The three-dimensional surface two-stage reconstruction measurement system of claim 8, wherein, A transverse connecting rod is further connected between the two Z-axis linear modules; A Z-axis perpendicularity adjusting assembly is further connected between the Z-axis linear module and the X-axis sliding seat, the Z-axis perpendicularity adjusting assembly comprises a spherical hinge connecting rod, a spherical hinge screw rod and a spherical hinge screw sleeve connected in sequence; The laser measurement end is angle-adjustable and translatable between the two Z-axis linear modules and connected to the hanging cross beam. The clamp is provided with a positioning structure matched with the workpiece to be measured.

10. A three-dimensional curved surface machining manufacturing system, characterized by comprising: The three-dimensional curved surface two-stage reconstruction measurement system comprises a machining execution system arranged on the side of the machining platform.

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