Measurement platform and measurement method for SPIV measurement

Abstract

The invention discloses a measuring platform and a measuring method for SPIV measurement, and belongs to the technical field of optical measurement. A measuring platform for SPIV measurement comprises a rigid mounting seat and a controller, a laser is arranged in the middle of the mounting seat and used for generating a laser slice for illuminating particles in a flow field, and high-speed cameras are arranged on the two sides of the laser respectively and used for collecting particle images. A fine adjustment structure for adjusting the height and angle of the high-speed camera is arranged on the mounting seat, the mounting seat is arranged on an adjusting mechanism, and the adjusting mechanism, the laser and the high-speed camera are electrically connected with the control system. By adopting the measurement platform and the measurement method for SPIV measurement, the problems of difficulty in switching measurement areas, low positioning precision of a camera and a laser, large repeated calibration workload, unstable system structure and the like in the existing SPIV measurement process are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical measurement, and in particular to a measurement platform and a measurement method for SPIV measurement. Background Art

[0002] Stereo Particle Image Velocimetry (SPIV), a non-contact, full-field, high-resolution three-dimensional velocity measurement method, has become a core tool in experimental fluid dynamics research in recent years. It has been widely used in a variety of research areas, including visualization of complex flow structures, investigation of turbulence characteristics, analysis of boundary layer development, and aerodynamic verification. Due to its instantaneous capture, high accuracy, and rich measurement information, it has become an essential flow field diagnostic technique in various wind tunnels, flumes, and jet test rigs. With the growing demand for high-precision experimental research, SPIV systems have expanded from single-point measurement to multi-point, large-field-of-view, and even dynamic scanning measurement. In this process, the stability and adjustability of the optical components in the system have become key factors limiting experimental accuracy and efficiency. In current engineering practice, SPIV measurement setups typically utilize a laser and high-speed camera mounted on a bracket outside the experimental area. To cover different measurement areas, researchers often need to manually move the object under test, the laser device, or the camera, and recalibrate the system each time. This cumbersome process can result in significant errors and can easily lead to optical path misalignment and data inconsistency.

[0003] Structural improvements to the SPIV platform system have primarily focused on enhancing the light source and optimizing the calibration method, while improvements in the spatial movement of the measurement platform, degree-of-freedom decoupling control, and ensuring optical path stability remain insufficient. Especially in multi-point measurement or dynamic tracking applications, fixed measurement systems can no longer meet comprehensive performance requirements such as a wide measurement range, strong optical axis consistency, and precise angle adjustment. Therefore, there is an urgent need for a three-dimensional adjustable platform system with high precision, multiple degrees of freedom, and fully automatic control capabilities to enable rapid and stable switching of the SPIV system between different measurement positions, avoid repeated calibration and manual errors, improve data consistency and measurement efficiency, and promote the widespread application of SPIV technology in complex experimental environments. Summary of the Invention

[0004] The purpose of the present invention is to provide a measurement platform and measurement method for SPIV measurement, which can solve the problems existing in the existing SPIV measurement process, such as difficulty in switching measurement areas, low positioning accuracy of cameras and lasers, large workload of repeated calibration, and unstable system structure.

[0005] To achieve the above objectives, the present invention provides a measurement platform for SPIV measurement, including a rigid mounting base and a controller. A laser is provided in the middle of the mounting base, and the laser is used to generate a laser sheet that illuminates particles in the flow field. A high-speed camera is provided on both sides of the laser, and the high-speed camera is used to collect particle images. The mounting base is provided with a fine-tuning structure for adjusting the height and angle of the high-speed camera. The mounting base is set on an adjustment mechanism, and the adjustment mechanism, laser and high-speed camera are all electrically connected to the control system.

[0006] Preferably, the fine-tuning structure includes a lifting seat and a pan-tilt head, the lifting seat is fixed on the mounting seat, the pan-tilt head is fixed on the lifting seat, the high-speed camera is fixed on the pan-tilt head, the height of the high-speed camera is adjusted by the lifting seat, and the tilt angle of the high-speed camera is adjusted by the pan-tilt head.

[0007] Preferably, the gimbal is a six-degree-of-freedom gimbal.

[0008] Preferably, the visual axis of the high-speed camera passes through the central area of ​​the laser sheet generated by the laser, forming a stereoscopic imaging configuration.

[0009] Preferably, the adjustment mechanism includes a rigid first adjustment structure, a second adjustment structure and a third adjustment structure, the first adjustment structure, the second adjustment structure and the third adjustment structure are arranged vertically in pairs, the second adjustment structure is arranged on the first adjustment structure, the third adjustment structure is arranged on the second adjustment structure, and the mounting seat is arranged on the third adjustment structure.

[0010] Preferably, the first adjustment structure includes a base, a first groove is provided in the middle of the upper surface of the base, a first screw rod is rotatably provided in the first groove, a first motor is provided at one end of the base to drive the first screw rod to rotate, a first slider adapted to the first screw rod is provided on the second adjustment structure, the first slider is located in the first groove and is slidably connected to the first groove, a first guide rail that guides the sliding of the second adjustment structure is provided on the base, and the first guide rail is provided in parallel with the first screw rod.

[0011] Preferably, the second adjustment structure includes a column, a second groove is provided in the middle of the side surface of the column, a second screw rod is rotatably provided in the second groove, a second motor is provided at one end of the column to drive the second screw rod to rotate, a second slider adapted to the second screw rod is provided on the third adjustment structure, the second slider is located in the second groove and is slidably connected to the second groove, a second guide rail that guides the sliding of the third adjustment structure is provided on the column, and the second guide rail is provided parallel to the second screw rod.

[0012] Preferably, the third adjustment structure includes a crossbeam, a third groove is provided in the middle of the side surface of the crossbeam, a third screw is rotatably provided in the third groove, a third motor is provided at one end of the crossbeam to drive the third screw to rotate, a third slider adapted to the third screw is provided on the slide seat, the third slider is located in the third groove and is slidably connected to the third groove, a third guide rail is provided on the crossbeam to guide the sliding of the slide seat, and the third guide rail is arranged parallel to the third screw rod; the mounting seat is fixedly provided on the rigid slide seat.

[0013] A measurement method for the above-mentioned measurement platform for SPIV measurement comprises the following steps:

[0014] S1. Set the target measurement path, initialize the adjustment mechanism, set the laser parameters, adjust the height of the high-speed camera and the angle between it and the laser; set the three-dimensional coordinate path of each measuring point through the control system, and position the mounting base to each measuring point in sequence according to the path;

[0015] S2. After the mount is positioned at the measuring point, the laser emits a laser sheet to illuminate the measured area. Two high-speed cameras synchronously capture particle images, capturing multiple image pairs at preset time intervals. Each image pair records the projection of the particle moving in the flow field over time. The image pair data is stored in the acquisition terminal of the control system and bound to the position information of the measuring point.

[0016] S3, the image processing module of the control system performs stereo correction and matching on the image pairs taken by the high-speed camera to reconstruct the three-dimensional velocity components of the particles;

[0017] S4. The control system summarizes the velocity field data of all measuring points to generate a complete three-dimensional velocity field distribution image; the measurement data and coordinate path are synchronously output to the SPIV analysis software platform for post-processing and flow field visualization.

[0018] Preferably, the relative position of the high-speed camera and the laser remains stable during the measurement process, and the positioning accuracy of the adjustment mechanism is ±0.01 mm.

[0019] The advantages and positive effects of the measurement platform and measurement method for SPIV measurement described in the present invention are:

[0020] 1. The present invention adopts a structure with a laser centered and two high-speed cameras symmetrically arranged. By integrating a three-axis servo drive and a high-precision guide rail adjustment mechanism, it achieves high-precision switching operation of the measurement area while maintaining the relative position of the high-speed camera and the laser unchanged. This effectively avoids the optical axis offset and repeated calibration problems caused by frequent movement of optical equipment in traditional systems, ensures the consistency of the optical geometric structure during the three-dimensional velocity field measurement, and thus significantly improves data accuracy and comparability.

[0021] 2. This invention utilizes a servo motor combined with a closed-loop linear scale control system to achieve ±0.01mm precision movement of the mounting base in the three orthogonal directions of X, Y, and Z. The mounting base uses a rigid connection to secure the laser and high-speed camera, and incorporates position limits and locking mechanisms to ensure the stability of the system's internal optical path during multi-point measurement or automated scanning. By presetting the control system's path and measurement points, automated, multi-region, and highly repeatable SPIV measurements are achieved, effectively improving the efficiency of acquiring three-dimensional velocity data in complex flow fields.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the three-dimensional structure of an embodiment of the present invention;

[0024] Figure 2 It is a front view structural schematic diagram of an embodiment of the present invention.

[0025] Reference numerals

[0026] 1. Base; 2. Column; 3. Beam; 4. Slide; 5. Mounting seat; 6. Laser; 7. High-speed camera; 8. Lifting seat; 9. Pan / tilt head; 10. First motor; 11. First screw rod; 12. First guide rail; 13. First slider; 14. Second motor; 15. Second screw rod; 16. Second guide rail; 17. Third motor; 18. Third screw rod; 19. Third guide rail. DETAILED DESCRIPTION

[0027] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is usually placed when in use. These are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention. In the description of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the internal parts of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. In the event of any inconsistency, the meaning described in this specification or the meaning derived from the contents recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0029] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0030] like Figure 1 、 Figure 2 A measurement platform for SPIV measurement is shown. It includes a rigid mounting base 5 and a controller. A laser 6 is fixedly mounted in the center of the mounting base 5. Laser 6 is used to generate a laser sheet that illuminates particles in the flow field. A high-speed camera 7 is mounted on either side of the laser 6 to capture particle images. The mounting base 5 is mounted on an adjustment mechanism. The adjustment mechanism, laser 6, and high-speed camera 7 are all electrically connected to a control system.

[0031] Mounting base 5 is equipped with a fine-tuning mechanism for adjusting the height and angle of high-speed camera 7. The fine-tuning mechanism comprises a lifting base 8 and a platform 9. Lifting base 8 is fixed to mounting base 5. Lifting base 8 can utilize a conventional lifting hinge structure. Platform 9 is fixed to lifting base 8, and high-speed camera 7 is fixed to platform 9. The height of high-speed camera 7 is adjusted via lifting base 8, while the tilt angle of high-speed camera 7 is adjusted via platform 9.

[0032] The gimbal 9 is a six-degree-of-freedom gimbal 9. In addition to fine-tuning the angle of the gimbal 9, the height and position of the gimbal 9 can also be fine-tuned.

[0033] The visual axis of high-speed camera 7 passes through the center of the laser sheet generated by laser 6, forming a three-dimensional imaging configuration. Two high-speed cameras 7 are placed on either side of laser 6, suitable for measuring the three-dimensional velocity field structure of narrow and long flow fields (such as jet outlets, wake vortex zones, and boundary layer development zones). The relative position and angle between laser 6 and the camera are fixed using mechanical stoppers and positioning pins after initial system calibration. This relative position and structure remain unchanged during movement, ensuring consistency between the laser light sheet and the camera field of view from one measurement point to another.

[0034] The adjustment mechanism includes a rigid first adjustment structure, a second adjustment structure and a third adjustment structure. The first adjustment structure, the second adjustment structure and the third adjustment structure are arranged vertically in pairs. The second adjustment structure is arranged on the first adjustment structure, the third adjustment structure is arranged on the second adjustment structure, and the mounting seat 5 is arranged on the third adjustment structure.

[0035] The first adjustment structure includes a base 1, a first groove is provided in the middle of the upper surface of the base 1, and a first screw rod 11 is rotatably provided in the first groove through a bearing. A first motor 10 is fixedly provided at one end of the base 1 to drive the first screw rod 11 to rotate. A first slider 13 adapted to the first screw rod 11 is fixedly provided on the second adjustment structure, and a first threaded hole adapted to the first screw rod 11 and passed through the first screw rod 11 is provided on the first slider 13. The first screw rod 11 drives the second adjustment structure to slide along the length direction of the first screw rod 11 through the first threaded hole. The first slider 13 is located in the first groove and is slidably connected to the first groove. A first guide rail 12 that guides the sliding of the second adjustment structure is fixedly provided on the base 1, and the first guide rail 12 is arranged parallel to the first screw rod 11.

[0036] The second adjustment structure includes a column 2, which is arranged perpendicular to the base 1. A second groove is provided in the middle of the side of the column 2, and a second screw rod 15 is rotatably provided in the second groove through a bearing. A second motor 14 is fixedly provided at one end of the column 2 to drive the second screw rod 15 to rotate. The third adjustment structure is provided with a second slider that is adapted to the second screw rod 15, and the second slider is provided with a second threaded hole that is adapted to the second screw rod 15 and allows the second screw rod 15 to pass through. The second screw rod 15 drives the third adjustment structure to slide along the length direction of the second screw rod 15 through the second threaded hole. The second slider is located in the second groove and is slidably connected to the second groove. A second guide rail 16 that has a guiding effect on the sliding of the third adjustment structure is fixedly provided on the column 2, and the second guide rail 16 is arranged parallel to the second screw rod 15.

[0037] The third adjustment structure includes a crossbeam 3, which is perpendicular to both the column 2 and the base 1. A third groove is provided in the middle of the side of the crossbeam 3, in which a third screw rod 18 is rotatably provided via a bearing. A third motor 17 is fixedly provided at one end of the crossbeam 3 to drive the third screw rod 18 to rotate. A third slider adapted to the third screw rod 18 is provided on the slide 4, and a third threaded hole adapted to the third screw rod 18 and through which the third screw rod 18 passes is provided on the third slider. The third screw rod 18 drives the slide 4 to slide along the length direction of the third screw rod 18 through the third threaded hole. The third slider is located in the third groove and is slidably connected to the third groove. A third guide rail 19 is provided on the crossbeam 3 to guide the sliding of the slide 4. The third guide rail 19 is arranged parallel to the third screw rod 18. The mounting seat 5 is fixedly provided on the rigid slide 4.

[0038] The first motor 10, second motor 14, and third motor 17 are all electrically connected to a control system. The control system's servo system, combined with a grating scale, forms a closed-loop feedback structure, achieving a positioning accuracy of ±0.01mm. A dust cover and shock-absorbing pads are installed on the outside of the adjustment mechanism to mitigate environmental impacts.

[0039] The control system includes a laser 6 control module, a high-speed camera 7 control module, an image acquisition terminal, and an image processing module. The laser 6 control module is used to set the parameters and switch of laser 6. The high-speed camera 7 control module is connected to the dual high-speed cameras 7, synchronously triggering the cameras to capture particle images and adjusting camera parameters such as exposure time and frame rate. The image acquisition terminal receives image data transmitted by the high-speed cameras 7 and stores it in conjunction with the measurement point location information. The image processing module performs stereo correction, matching, and three-dimensional velocity component reconstruction on the image pairs, and its built-in algorithm supports real-time data processing. Each module of the control system adopts existing technologies as needed.

[0040] The measurement method based on the above-mentioned measurement platform for SPIV measurement includes the following steps:

[0041] S1. Set the target measurement path, initialize the adjustment mechanism, set the parameters of the laser 6, and adjust the height of the high-speed camera 7 and the angle between it and the laser 6. The three-dimensional coordinate path of each measuring point is set by the control system, and the mounting base 5 is positioned to each measuring point in sequence according to the path.

[0042] S2. After the mounting base 5 is positioned at the measuring point, the laser 6 emits a laser sheet to illuminate the measured area, and the two high-speed cameras 7 synchronously collect particle images, and multiple image pairs are collected at preset time intervals; each frame of the image pair records the projection of the particle moving in the flow field over time, and the image pair data is stored in the acquisition end of the control system and bound to the position information of the measuring point.

[0043] S3. The image processing module of the control system performs stereo correction and matching on the image pairs taken by the high-speed camera 7 to reconstruct the three-dimensional velocity components of the particles.

[0044] S4: The control system aggregates the velocity field data from all measurement points to generate a complete 3D velocity field distribution image. The system can repeatedly execute multiple scan cycles of the 3D coordinate path for each measurement point to meet time-series measurement requirements. The measurement data and coordinate path are synchronously output to the SPIV analysis software platform for post-processing and flow field visualization.

[0045] As the laser 6 switches between measurement points, it maintains a locked state with the high-speed camera 7, eliminating the need for recalibration of the optical path and system recalibration. This significantly reduces operation time and prevents error accumulation during multi-point experimental measurements. The system control terminal enables one-click operation through pre-set programs, with features such as automatic looping, multi-segment measurement, and path retracement, significantly improving overall experimental efficiency.

[0046] The measurement platform's compact design reduces footprint by approximately 40% compared to traditional devices, making it ideal for deployment in space-constrained experimental environments such as wind tunnels, flume walls, and jet flow systems. Bolted mounting and a reinforced retaining structure for the laser and high-speed camera allow for flexible changes in camera model, laser parameters, and path control logic based on measurement requirements.

[0047] Therefore, the measurement platform and measurement method for SPIV measurement described in the present invention solve the problems existing in the existing SPIV measurement process, such as difficulty in switching measurement areas, low positioning accuracy of cameras and lasers, large workload of repeated calibration, and unstable system structure.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A measurement platform for SPIV measurement, characterized by: It includes a rigid mounting base and a controller. A laser is set in the middle of the mounting base. The laser is used to generate a laser sheet that illuminates the particles in the flow field. A high-speed camera is set on both sides of the laser. The high-speed camera is used to collect particle images. The mounting base is provided with a fine-tuning structure for adjusting the height and angle of the high-speed camera. The mounting base is set on an adjustment mechanism. The adjustment mechanism, laser and high-speed camera are all electrically connected to the control system.

2. A measurement platform for SPIV measurement according to claim 1, characterized in that: The fine-tuning structure includes a lifting seat and a pan-tilt platform. The lifting seat is fixed on the mounting seat, the pan-tilt platform is fixed on the lifting seat, and the high-speed camera is fixed on the pan-tilt platform. The height of the high-speed camera is adjusted by the lifting seat, and the tilt angle of the high-speed camera is adjusted by the pan-tilt platform.

3. A measurement platform for SPIV measurement according to claim 2, characterized in that: The pan-tilt platform is a six-degree-of-freedom pan-tilt platform.

4. The measurement platform for SPIV measurement according to claim 1, characterized in that: The visual axis of the high-speed camera passes through the central area of ​​the laser sheet generated by the laser, forming a stereoscopic imaging configuration.

5. The measurement platform for SPIV measurement according to claim 1, characterized in that: The adjustment mechanism includes a rigid first adjustment structure, a second adjustment structure and a third adjustment structure. The first adjustment structure, the second adjustment structure and the third adjustment structure are arranged vertically in pairs. The second adjustment structure is arranged on the first adjustment structure, the third adjustment structure is arranged on the second adjustment structure, and the mounting seat is arranged on the third adjustment structure.

6. The measurement platform for SPIV measurement according to claim 5, characterized in that: The first adjustment structure includes a base, a first groove is provided in the middle of the upper surface of the base, a first screw rod is rotatably provided in the first groove, a first motor is provided at one end of the base to drive the first screw rod to rotate, a first slider adapted to the first screw rod is provided on the second adjustment structure, the first slider is located in the first groove and is slidably connected to the first groove, a first guide rail that guides the sliding of the second adjustment structure is provided on the base, and the first guide rail is provided in parallel with the first screw rod.

7. The measurement platform for SPIV measurement according to claim 6, characterized in that: The second adjustment structure includes a column, a second groove is provided in the middle of the side surface of the column, a second screw rod is rotatably provided in the second groove, a second motor is provided at one end of the column to drive the second screw rod to rotate, a second slider adapted to the second screw rod is provided on the third adjustment structure, the second slider is located in the second groove and is slidably connected to the second groove, a second guide rail is provided on the column that guides the sliding of the third adjustment structure, and the second guide rail is arranged parallel to the second screw rod.

8. The measurement platform for SPIV measurement according to claim 7, characterized in that: The third adjustment structure includes a crossbeam, a third groove is provided in the middle of the side surface of the crossbeam, a third screw rod is rotatably provided in the third groove, a third motor is provided at one end of the crossbeam to drive the third screw rod to rotate, a third slider adapted to the third screw rod is provided on the slide seat, the third slider is located in the third groove and is slidably connected to the third groove, a third guide rail is provided on the crossbeam to guide the sliding of the slide seat, and the third guide rail is arranged parallel to the third screw rod; the mounting seat is fixedly provided on the rigid slide seat.

9. A measurement method based on a measurement platform for SPIV measurement according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Set the target measurement path, initialize the adjustment mechanism, set the laser parameters, adjust the height of the high-speed camera and the angle between it and the laser; set the three-dimensional coordinate path of each measuring point through the control system, and position the mounting base to each measuring point in sequence according to the path; S2. After the mount is positioned at the measuring point, the laser emits a laser sheet to illuminate the measured area. Two high-speed cameras synchronously capture particle images, capturing multiple image pairs at preset time intervals. Each image pair records the projection of the particle moving in the flow field over time. The image pair data is stored in the acquisition terminal of the control system and bound to the position information of the measuring point. S3, the image processing module of the control system performs stereo correction and matching on the image pairs taken by the high-speed camera to reconstruct the three-dimensional velocity components of the particles; S4. The control system summarizes the velocity field data of all measuring points to generate a complete three-dimensional velocity field distribution image; the measurement data and coordinate path are synchronously output to the SPIV analysis software platform for post-processing and flow field visualization.

10. The measurement method of a measurement platform for SPIV measurement according to claim 9, characterized in that: During the measurement process, the relative position of the high-speed camera and the laser remains stable, and the positioning accuracy of the adjustment mechanism is ±0.01mm.

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