Variable magnification field of view structured light measurement device and method

Abstract

The application discloses a variable-magnification variable-field-of-view structured light measuring device and method, and relates to the technical field of structured light measurement.The device comprises a structured light projector group, a high-speed acquisition camera group, a multi-magnification telecentric lens and an FPGA controller.Four structured light projectors are arranged in the structured light projector group, and are electrically connected with the FPGA controller, and are used for receiving a trigger signal and coded pattern data of the FPGA controller.Four high-speed acquisition cameras are arranged in the high-speed acquisition camera group, and are electrically connected with the FPGA controller, and are used for receiving a synchronous trigger signal of the FPGA controller.The FPGA controller is a time sequence control and data processing core of the measuring device.The application can avoid point cloud errors caused by the fact that the projected stripes are blocked, and can meet the requirements of different measuring fields of view, different areas and different measuring accuracies, and is particularly suitable for samples which are densely arranged in the middle, small in size, sparsely arranged at the edges and large in size.

Description

Technical Field

[0001] This invention relates to the field of structured light measurement technology, and in particular to a structured light measurement device and method with variable magnification and variable field of view. Background Technology

[0002] Structured light 3D measurement technology, also known as active triangulation, works by projecting a coded pattern onto the surface of the object being measured using a projector. A camera then captures a deformed fringe image modulated by the object's shape. This modulated image contains the object's height information, thus allowing the acquisition of the object's 3D shape.

[0003] In structured light 3D reconstruction, traditional measurement methods often use a single camera with multiple projections or a single projection with multiple cameras. Because there is a certain angular relationship between the projection and the camera and the object, it is difficult for a single projection and camera to measure every position of the object, resulting in the loss of some height information of the object.

[0004] Conventional structured light measurement systems have only one field of view, making them incompatible with samples of varying sizes and regions. This system employs a four-camera, four-projection structure, enabling comprehensive 3D reconstruction measurements of objects with different field of view sizes and precision, achieving variable magnification and variable field of view for higher accuracy. The central telecentric lens has four different magnifications, and the four high-speed cameras each correspond to a different magnification, achieving variable magnification and variable field of view, resulting in varying measurement accuracies. It can accommodate different cameras corresponding to all four structured light projections, or different cameras corresponding to different structured light projections, offering broad adaptability and the ability to measure a wide variety of samples. Summary of the Invention

[0005] This invention provides a structured light measurement device with variable magnification and variable field of view, comprising: a structured light projector group, a high-speed acquisition camera group, a multi-magnification telecentric lens (3), and an FPGA controller (4); the structured light projector group is equipped with four structured light projectors, all of which are electrically connected to the FPGA controller (4) to receive trigger signals and encoded pattern data from the FPGA controller (4) and realize precise control of projection timing and pattern content; the high-speed acquisition camera group is equipped with four high-speed acquisition cameras, all of which are electrically connected to the FPGA controller (4) to receive synchronous trigger signals from the FPGA controller (4) and realize independent trigger acquisition or multi-camera synchronous trigger acquisition; the FPGA controller (4) is the core of timing control and data processing of the measurement device.

[0006] The variable magnification and variable field of view structured light measurement device described above, wherein the structured light projector group includes: a first structured light projector (11), a second structured light projector (12), a third structured light projector (13) and a fourth structured light projector (14); the four structured light projectors are symmetrically distributed in a ring around the outer periphery of the multi-magnification telecentric lens (3), and the projection optical axes of all projectors are directed toward the measurement station of the object to be measured.

[0007] The structured light measurement device with variable magnification and variable field of view as described above, wherein the internal structure of the multi-magnification telecentric lens (3) includes a lens barrel, a telecentric objective lens group arranged sequentially from the object side to the image side along the main imaging optical axis, and a beam splitting optical path assembly.

[0008] The structured light measurement device with variable magnification and variable field of view as described above, wherein the beam splitting optical path component includes a first beam splitting prism (31), a second beam splitting prism (32), and a third beam splitting prism (33). The three beam splitting prisms are arranged coaxially along the main imaging optical axis to split the incident light reflected by the object under test into four imaging optical paths with equal optical paths, and the four imaging optical paths correspond to four different fixed optical magnifications.

[0009] The variable magnification and variable field of view structured light measurement device described above, wherein the high-speed acquisition camera group includes: a first high-speed acquisition camera (21), a second high-speed acquisition camera (22), a third high-speed acquisition camera (23) and a fourth high-speed acquisition camera (24); the four high-speed acquisition cameras are fixedly connected one-to-one with the four imaging optical paths of the multi-magnification telecentric lens (3) through a standard C-type interface.

[0010] As described above, in the structured light measurement device with variable magnification and variable field of view, in terms of optical path transmission, the light reflected by the object under test is collimated by the telecentric objective lens group in the multi-magnification telecentric lens (3), and then reflected by the first beam splitter (31) to the photosensitive chip of the first high-speed acquisition camera (21), reflected by the second beam splitter (32) to the photosensitive chip of the second high-speed acquisition camera (22), reflected by the third beam splitter (33) to the photosensitive chip of the third high-speed acquisition camera (23), and finally the transmitted light is directly incident on the photosensitive chip of the fourth high-speed acquisition camera (24), thus completing the synchronous imaging of four different magnifications.

[0011] The present invention also provides a structured light measurement method with variable magnification and field of view, applied in the FPGA controller of the structured light measurement device with variable magnification and field of view as claimed in claim , comprising: Step S10: Calibrate the inherent hardware parameters of the structured light measurement device and save them to the on-chip non-volatile memory of the FPGA controller; Step S20: Receive the measurement request for the object under test from the host computer and analyze the geometric features of the object under test; Step S30: Retrieve the fixed inherent hardware parameters, execute the magnification-field of view-accuracy linkage matching algorithm, and output the optimal measurement scheme according to the measurement requirements and geometric features of the object under test; Step S40: Based on the optimal measurement scheme output, perform linkage control on the structured light measurement device to acquire the deformed stripe image after height modulation of the object under test; Step S50: Perform phase calculation and three-dimensional coordinate transformation on the acquired deformed stripe image, and output the final three-dimensional point cloud model.

[0012] The beneficial effects achieved by this invention are as follows: Compared with existing single-camera multi-projection systems and single-projection multi-camera systems, this invention uses four projectors to project phase-encoded fringes and four cameras to perform structured light 3D reconstruction of objects in multiple dimensions, which can avoid point cloud errors caused by the occlusion of projected fringes; different cameras correspond to telecentric lenses with different magnifications, which can meet the needs of different measurement fields of view, different regions, and different measurement accuracies, and are particularly suitable for samples that are dense in the middle, small in size, sparse at the edges, and large in size; different magnification lenses and camera fields of view can also correspond to different projection image sizes, which can achieve better structured light resolution while achieving different 2D and 3D measurement accuracies. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0014] Figure 1 This is a schematic diagram of a structured light measurement device with variable magnification and variable field of view provided in Embodiment 1 of this application; Figure 2 This is the optical path diagram of the structured light measurement device with variable magnification and variable field of view provided in Embodiment 1 of this application; Figure 3 This is a flowchart of a structured light measurement method with variable magnification and variable field of view provided in Embodiment 2 of this application. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1 like Figure 1 As shown, Embodiment 1 of this application provides a structured light measurement device with variable magnification and variable field of view, including: a structured light projector group, a high-speed acquisition camera group, a multi-magnification telecentric lens 3, and an FPGA controller 4; the structured light projector group is equipped with four structured light projectors, all of which are electrically connected to the FPGA controller 4 via coaxial cables, and are used to receive trigger signals and coded pattern data from the FPGA controller 4 to achieve precise control of projection timing and pattern content; the high-speed acquisition camera group is equipped with four high-speed acquisition cameras, all of which are electrically connected to the FPGA controller 4 via gigabit network interfaces or Camera Link interfaces, and are used to receive synchronous trigger signals from the FPGA controller 4, enabling independent trigger acquisition or multi-camera synchronous trigger acquisition; the FPGA controller 4 is the core of timing control and data processing of the measurement device.

[0017] The structured light projector group includes: a first structured light projector 11, a second structured light projector 12, a third structured light projector 13, and a fourth structured light projector 14. The four structured light projectors are symmetrically distributed in a ring around the outer periphery of the multi-magnification telecentric lens 3. The projection optical axes of all projectors are oriented towards the measurement station of the object to be measured, and each projection optical axis forms a preset angle of 15° to 45° with the main imaging optical axis of the multi-magnification telecentric lens 3. This angle can be adapted and adjusted according to the measurement baseline and depth of field requirements, which ensures the effective baseline length of the active triangulation method measurement and minimizes the mutual occlusion between projection and imaging.

[0018] like Figure 2 As shown, the internal structure of the multi-magnification telecentric lens 3 includes a lens barrel, a telecentric objective lens group arranged sequentially from the object side to the image side along the main imaging optical axis, and a beam splitting optical path assembly; wherein the beam splitting optical path assembly includes a first beam splitting prism 31, a second beam splitting prism 32, and a third beam splitting prism 33, the three beam splitting prisms being arranged coaxially along the main imaging optical axis to split the incident light reflected from the object under test into four imaging optical paths with equal optical path lengths, and the four imaging optical paths corresponding to four different fixed optical magnifications respectively; In this embodiment, the optical magnification of the four imaging optical paths is exemplarily set to 0.15X, 0.3X, 0.45X, and 0.6X. The magnification increases sequentially from the object side to the image side along the main imaging optical axis, corresponding to a sequential decrease in the field of view (FOV) and a sequential increase in theoretical measurement accuracy. By integrating multiple magnification optical paths into a single lens, variable magnification and variable field of view imaging measurements can be achieved without changing the lens or adjusting the position of the object under test. Simultaneously, the four optical paths employ an equal optical path design to ensure that all four imaging paths can achieve clear focus across the full frame without any defocus or blurring issues.

[0019] The high-speed acquisition camera group includes: a first high-speed acquisition camera 21, a second high-speed acquisition camera 22, a third high-speed acquisition camera 23, and a fourth high-speed acquisition camera 24. The four high-speed acquisition cameras are fixedly connected to the four imaging optical path interfaces of the multi-magnification telecentric lens 3 through standard C-type interfaces, specifically: the first high-speed acquisition camera 21 corresponds to the 0.15X magnification imaging optical path, the second high-speed acquisition camera 22 corresponds to the 0.3X magnification imaging optical path, the third high-speed acquisition camera 23 corresponds to the 0.45X magnification imaging optical path, and the fourth high-speed acquisition camera 24 corresponds to the 0.6X magnification imaging optical path.

[0020] In terms of optical path transmission, the light reflected from the object under test is collimated by the telecentric objective lens group in the multi-magnification telecentric lens 3, then reflected by the first beam splitter prism 31 to the photosensitive chip of the first high-speed acquisition camera 21, reflected by the second beam splitter prism 32 to the photosensitive chip of the second high-speed acquisition camera 22, reflected by the third beam splitter prism 33 to the photosensitive chip of the third high-speed acquisition camera 23, and finally the transmitted light is directly incident on the photosensitive chip of the fourth high-speed acquisition camera 24, completing the synchronous imaging of four different magnifications.

[0021] The high-speed acquisition camera in this embodiment uses a CMOS industrial camera with a global shutter, an acquisition frame rate of no less than 30fps, and a pixel resolution that matches the projection resolution of the corresponding magnification. It can accurately acquire deformed structured light stripe images after the surface morphology of the object under test is modulated.

[0022] The system imaging optical path principle of this embodiment is as follows: The object to be measured is fixedly placed at the measurement station and is within the object-side depth of field of the multi-magnification telecentric lens 3. Four structured light projectors project preset coded structured light stripes onto the surface of the object to be measured from different angles. The stripe pattern is deformed by the three-dimensional shape modulation of the surface of the object to be measured, and the deformed stripes carry the height information of the object to be measured. After the modulated stripes carrying the height information are reflected by the surface of the object to be measured, they are incident on the telecentric objective lens group of the multi-magnification telecentric lens 3, and after collimation, they form parallel light that enters the beam splitter assembly.

[0023] The incident parallel light first reaches the first beam splitter 31, which reflects a portion of the incident light to the photosensitive chip of the first high-speed acquisition camera 21 according to a preset splitting ratio, forming a first imaging optical path with a magnification of 0.15X. The remaining transmitted light continues to propagate along the main imaging optical axis to the second beam splitter 32, which reflects a portion of the incident light to the photosensitive chip of the second high-speed acquisition camera 22 according to a preset splitting ratio, forming a second imaging optical path with a magnification of 0.3X. The remaining transmitted light continues to propagate along the main imaging optical axis to the third beam splitter 33, which reflects a portion of the incident light to the photosensitive chip of the third high-speed acquisition camera 23 according to a preset splitting ratio, forming a third imaging optical path with a magnification of 0.45X. Finally, the remaining transmitted light directly enters the photosensitive chip of the fourth high-speed acquisition camera 24 along the main imaging optical axis, forming a fourth imaging optical path with a magnification of 0.6X.

[0024] The four imaging optical paths maintain an equal optical path design throughout, ensuring that all four high-speed acquisition cameras can obtain clear full-frame images at their respective magnifications. At the same time, by integrating multiple magnification optical paths through a single lens, synchronous imaging with four different measurement fields and different measurement accuracies is achieved at the same measurement station. Variable magnification and variable field of view three-dimensional measurement can be completed without hardware disassembly and sample displacement. Example

[0025] like Figure 3 As shown, Embodiment 2 of this application provides a structured light measurement method with variable magnification and field of view, applied in the FPGA controller, including: Step S10: Calibrate the inherent hardware parameters of the structured light measurement device and save them to the on-chip non-volatile memory of the FPGA controller; For the four equal-path imaging optical paths of the multi-magnification telecentric lens in the structured light measurement device with variable magnification and variable field of view, optical parameter calibration is completed using a standard calibration board to obtain four sets of one-to-one corresponding inherent hardware parameters, numbered i=1, 2, 3, and 4 in ascending order of magnification. Specifically, these include: The value of the i-th multiplier : Fixed constants, in order as follows ; The imaging field of view corresponding to the i-th magnification level The unit is mm. The calibrated constant is negatively correlated with the magnification and satisfies... ; The theoretical measurement accuracy corresponding to the i-th magnification level Unit is The calibrated constant (i.e., measurement error) that is negatively correlated with the magnification satisfies ; The object depth of field corresponding to the i-th magnification level The unit is mm. It is a fixed constant that is negatively correlated with the magnification obtained from calibration, and represents the axial distance range in which the object-side image is clear.

[0026] For the hardware architecture of the variable magnification and variable field of view structured light measurement device, which is "three-stage beam splitting prism, four-magnification common principal optical axis optical path + four-path equal optical path multi-camera synchronous imaging", two more exclusive coupling parameters are calibrated: Spectrophotometer intensity attenuation coefficient : with multiplier value A fixed constant with one-to-one correspondence characterizes the light intensity transmittance after passing through the beam splitter in optical paths of different magnifications. The smaller the coefficient, the more severe the light intensity attenuation, the lower the image signal-to-noise ratio, and the greater the attenuation of actual measurement accuracy relative to ideal accuracy. A standard integrating sphere uniform light source is used and placed at the center of the depth of field on the object side of the multi-magnification telecentric lens. The light intensity output by the light source is fixed to a traceable standard value. ; Sequentially read the incident light intensity of the photosensitive chips of four high-speed acquisition cameras at corresponding magnification. Through the formula: The attenuation coefficient at the corresponding magnification is calculated and satisfies the following conditions: It is strictly negatively correlated with increasing multiplier; Multiple ratio feature complementarity coefficient Characterizing the magnification value With the multiplier value The higher the coefficient, the stronger the complementary imaging capability between the two magnifications in terms of field of view, accuracy, and depth of field. This results in better fusion of the global contour and local details after simultaneous measurement. It also indicates the multiplier number, and A standard calibration plate, containing both large-scale global contours and micron-level local features, is placed at the center of the measurement station; for any combination of two magnification values... Simultaneous imaging images of the calibration plate were acquired at two different magnification levels, and the field-of-view overlap of the global contour was calculated. Complementarity of local feature accuracy Depth of field coverage overlap Three sub-parameters, through a weighted linear model: The complementarity coefficient was calculated; where Contribution weights preset for the system ; , Multiplier value Within the imaging field of view, the effective imaging area of ​​the calibration board's global contour, in mm², is determined by the magnification value. The calibration board image captured by the corresponding camera is obtained through edge detection and extraction. Multiplier value and multiplier value The overlapping area of ​​the effective imaging region of the global contour of the calibration board in the imaging field of view, in units of , , They are respectively the i-th level and the i-th level. The theoretical measurement accuracy of the magnification ratio. , These are the multiplier values. , The attenuation coefficient of the spectral intensity. To calibrate the standard reflectivity of the plate surface; , The object depth of field corresponds to the i-th magnification level. For the i-th multiplier and the i-th The magnification corresponds to the axial length of the overlapping interval of the object's depth of field.

[0027] The calibration results are stored in the on-chip non-volatile memory of the FPGA controller for real-time retrieval.

[0028] Step S20: Receive the measurement request for the object under test from the host computer and analyze the geometric features of the object under test; The FPGA controller receives the measurement requirements parameters of the object under test from the host computer via a high-speed communication interface. These parameters serve as rigid constraint inputs for the magnification-field-of-view-accuracy linkage matching algorithm, specifically including: Target measurement accuracy Unit is This refers to the upper limit of measurement accuracy requirements specified by the user. Maximum measurement range The unit is mm, which represents the maximum size requirement of the measurement area of ​​the object being measured, as specified by the user. Average reflectance of the surface of the object being measured : Obtained from user input or pre-collection calibration.

[0029] Simultaneously, the FPGA controller triggers the first high-speed acquisition camera corresponding to the 0.15X magnification, and synchronously triggers all four structured light projectors to project a global calibration pattern, completing a large-field-of-view pre-scan of the object under test. Based on the pre-scanned image, the geometric feature parameters of the object under test are extracted through edge detection and initial point cloud calculation, specifically including: Maximum external dimensions of the object under test The unit is mm, which represents the maximum length of the circumscribed rectangle of the object being measured within the measurement plane. Minimum geometric feature size of the object under test The unit is mm, and it represents the circumscribed dimension of the smallest geometric feature of the object being measured. The received and extracted parameters are temporarily stored in the on-chip RAM of the FPGA controller.

[0030] Step S30: Retrieve the fixed inherent hardware parameters, execute the magnification-field of view-accuracy linkage matching algorithm, and output the optimal measurement scheme according to the measurement requirements and geometric features of the object under test; The FPGA controller calls the inherent hardware constants and dedicated coupling parameters fixed in step S10, and the input parameters obtained in step S20, and completes the calculation through the magnification-field-of-view-accuracy linkage matching algorithm. It directly outputs a measurement scheme that the measurement device can directly execute, solving the technical pain points of accuracy deviation caused by beam splitting attenuation and the inability to fully utilize the advantages of multi-magnification synchronous imaging in the device described in Embodiment 1. The calculation process is specifically divided into the following sub-steps: Step S31: Based on the four fixed multiplier values, generate all non-empty multiplier combinations, and then filter out the valid multiplier combinations through coverage integrity verification; For four fixed multiplier values Generate all non-empty subsets, each subset corresponding to a multiplier combination C, where the number of multiplier values ​​m within the combination ranges from 1 to 2. It covers all scenarios where single, double, triple, and quadruple multipliers are fully enabled; Based on the fixed inherent hardware parameters and the geometric characteristics of the object under test, each magnification value is calculated. Actual measurement accuracy and feature resolution threshold , ,in To calibrate the standard reflectivity of the plate, This represents the theoretical measurement accuracy corresponding to the i-th magnification level. Multiplier value The attenuation coefficient of the spectral intensity. denoted as the average reflectance of the surface of the object being measured, and i is the magnification number; ,in The feature resolution coefficient is preset for the system (the value in this implementation is 2). Unit conversion factor (to (Convert to mm) For each leverage combination C, perform the following coverage integrity check in sequence: Joint coverage verification of the field of view: Define the joint effective field of view of combination C. For the imaging field of view corresponding to all magnifications within the combination. The maximum value requires the joint effective field of view of the ratio combination C. It must completely cover the maximum external dimensions of the object being tested. And not exceeding the maximum measurement range specified by the user. ,Right now ; Global accuracy achievable verification: Define the globally optimal achievable accuracy of combination C. For the actual measurement accuracy of all magnifications within the combination. The minimum value (i.e., the highest precision) requires that the globally achievable highest precision of the combination C must be better than the user-specified target precision upper limit. To meet core measurement needs, namely ; Full feature distinguishability verification: Define the minimum distinguishable feature threshold of combination C. Threshold for distinguishing features within the combination and across all magnifications The minimum value requires that the combination C must be able to stably distinguish the smallest geometric feature of the measured object, avoiding the loss of key morphological information, that is... .

[0031] All ratio combinations that simultaneously satisfy all three verification rules of the coverage integrity check will be included in the effective ratio combination set. .

[0032] Step S32: Based on the pre-constructed multi-rate optimization function, select the optimal activation rate combination from the filtered effective rate combinations; First, regarding the effective multiplier combination set Each valid combination Three sub-evaluation factors normalized to the [0,1] interval are constructed, specifically including: Precision performance factor Characteristic Combination To achieve a balance between accuracy and redundancy, a Gaussian function design is employed to avoid excessive accuracy redundancy at the expense of measurement efficiency. The calculation formula is as follows: ,in To meet the accuracy requirements, , The upper limit of target precision specified by the user. For combination Globally optimal achievable accuracy The system is preset with the optimal accuracy (in this embodiment, the value is 1.5, which means that the actual accuracy is 50% higher than the requirement, taking into account both margin and efficiency). This is the Gaussian bandwidth coefficient (0.8 in this embodiment); Feature complementary performance factor Characteristic Combination The global-local feature complementarity between multiple magnifications is strongly bound to the hardware architecture of the three-level beam splitting four-magnification coaxial system of this invention. The calculation formula is as follows: ,in For combination The corresponding set of multiplier numbers, For combination The number of multiplier values ​​within, Multiplier value Sum The complementarity coefficient of the multiple ratio characteristic; Measuring efficiency factor Characteristic Combination The measurement time and data processing efficiency are optimized to avoid excessively long cycles caused by meaningless multi-rate activation. The calculation formula is as follows: .

[0033] Next, a multi-rate optimization function is constructed based on the above three sub-evaluation factors. ;in The weighting coefficients correspond to the measurement modes specified by the user. When the user specifies "precision priority mode", the weighting is assigned as follows: When the user specifies "efficiency-first mode", the weight allocation is as follows: When the user does not explicitly specify the measurement mode, the weight allocation is as follows: .

[0034] For effective multiplier combinations For each combination in the algorithm, its comprehensive optimization coefficient is calculated sequentially using a multi-rate optimization function. The combination with the largest comprehensive optimization coefficient is then selected as the optimal activation rate combination and returned, denoted as . .

[0035] Step S33: Perform the hardware parameter mapping process for the optimal activation rate combination to generate a complete measurement scheme; The magnification that has the largest field of view within the combination and can cover the global contour of the measured object is defined as the main reference magnification, which serves as the global coordinate system reference for 3D reconstruction. The remaining magnifications within the combination are defined as auxiliary magnifications, which are used to supplement the high-precision measurement of features at different scales and achieve multi-scale coverage of global and local features.

[0036] For the optimal activation multiplier combination Each enabled multiplier Based on its corresponding spectral intensity attenuation coefficient The mapping yields the corresponding hardware control parameters of the high-speed acquisition camera, specifically including: Exposure time ,in Using the baseline exposure time, this formula compensates for the light intensity attenuation caused by spectral dispersion. The smaller the attenuation coefficient, the longer the exposure time. Gain parameters: The primary reference gain is fixed at 1dB, while the secondary gain increases linearly with the magnification, up to a maximum of 6dB, to improve the image signal-to-noise ratio of high-magnification optical paths; Hardware control not enabled: All high-speed acquisition cameras with magnification other than the optimal combination are put into sleep mode (low power mode, no acquisition action).

[0037] The optimal combination of activation magnification (including each activation magnification value, the corresponding high-speed acquisition camera number, and the master / slave priority identifier) ​​and the hardware control parameter mapping results are compiled into a complete measurement scheme for output.

[0038] Step S40: Based on the optimal measurement scheme output, perform linkage control on the structured light measurement device to acquire the deformed stripe image after height modulation of the object under test; The FPGA controller, based on the step-by-step output measurement scheme, completes the hardware linkage control of the measurement device, and is fully compatible with the hardware interface and timing architecture of Embodiment 1, specifically including: Camera parameter configuration: For all high-speed acquisition cameras with enabled magnification, write the exposure time and gain parameters into the measurement scheme; for cameras that are not enabled, implement sleep control to reduce system power consumption; Fixed projector configuration: All four structured light projectors are used throughout the measurement process, with a pre-loaded four-step phase-shift coded structured light pattern, and the calibrated fixed projection angle remains unchanged; Synchronous timing control: The FPGA controller generates sub-microsecond synchronous trigger timing based on the on-chip high-stability crystal oscillator. It sends synchronous projection trigger signals to all four structured light projectors via coaxial cable and synchronous exposure trigger signals to all enabled high-speed acquisition cameras via Gigabit Ethernet / Camera Link interface. This ensures that the rising edges of the full projector projection and the acquisition of all enabled cameras are perfectly aligned, with a synchronization deviation of ≤500ns, which is suitable for the timing requirements of multi-magnification synchronous imaging.

[0039] Step S50: Perform phase calculation and 3D coordinate transformation on the acquired deformed stripe image, and output the final 3D point cloud model; All four structured light projectors synchronously project coded structured light patterns onto the surface of the object under test. The patterns deform due to modulation of the three-dimensional shape of the object. All activated high-speed acquisition cameras synchronously acquire the modulated deformed fringe images. The FPGA controller performs phase calculation and three-dimensional coordinate transformation on the fringe images at each activated magnification to obtain the three-dimensional point cloud data at the corresponding magnification. Using the global point cloud at the main reference magnification as the coordinate system reference, all high-precision point clouds from the auxiliary magnifications are accurately mapped to the main reference coordinate system. Weighted fusion is performed on the overlapping areas, and the fusion weight is related to the feature complementarity coefficient of the corresponding magnification. Positive correlation leads to a complete 3D point cloud model that is seamlessly fused across multiple scales.

[0040] For any point P within the overlapping region, its coordinates in the effective point cloud at each magnification are plotted. Its weighted fusion formula is expressed as: (X,Y,Z) are the final 3D coordinates after fusion. Let P be the set of overlap ratio numbers. The fusion weight for the i-th multiplier is... The calculation process is as follows: First, use the formula: Calculate the initial fusion weights for each multiplier. ,in Let P be the factorial number of point cloud overlaps. Multiplier value , The complementarity coefficient of the multiple ratio characteristics between them Multiplier value The attenuation coefficient of the spectral intensity. Multiplier value The actual measurement accuracy; subsequently, the calculated initial fusion weights... Normalization is performed to obtain the final fusion weights. .

[0041] Corresponding to the above embodiments, the present invention provides a computer storage medium, including: at least one memory and at least one processor; The memory is used to store one or more program instructions; A processor for running one or more program instructions to execute a structured light measurement method with variable magnification and field of view.

[0042] Corresponding to the above embodiments, this embodiment of the invention provides a computer-readable storage medium containing one or more program instructions, which are executed by a processor to provide a structured light measurement method with variable magnification and field of view.

[0043] The embodiments disclosed in this invention provide a computer-readable storage medium storing computer program instructions that, when executed on a computer, cause the computer to perform the aforementioned structured light measurement method with variable magnification and field of view.

[0044] In this embodiment of the invention, the processor can be an integrated circuit chip with signal processing capabilities. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0045] The various methods, steps, and logic diagrams disclosed in the embodiments of this invention can be implemented or executed. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The processor reads information from the storage medium and, in conjunction with its hardware, completes the steps of the above methods.

[0046] The storage medium can be memory, such as volatile memory or non-volatile memory, or may include both volatile and non-volatile memory.

[0047] Among them, non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory.

[0048] Volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (Synchlink DRAM, SLDRAM), and direct memory bus RAM (DRRAM).

[0049] The storage media described in the embodiments of the present invention are intended to include, but are not limited to, these and any other suitable types of memory.

[0050] Those skilled in the art will recognize that, in one or more of the examples above, the functions described in this invention can be implemented using a combination of hardware and software. When applied as software, the corresponding functions can be stored in a computer-readable medium or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein communication media include any medium that facilitates the transmission of computer programs from one place to another. Storage media can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0051] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solution of the present invention should be included within the scope of protection of the present invention.

Claims

1. A structured light measurement device with variable magnification and variable field of view, characterized in that, include: The structure light projector group, high-speed acquisition camera group, multi-magnification telecentric lens (3) and FPGA controller (4) are provided. The structure light projector group is equipped with four structure light projectors, all of which are electrically connected to the FPGA controller (4) to receive the trigger signal and coded pattern data from the FPGA controller (4) and realize precise control of the projection timing and pattern content. The high-speed acquisition camera group is equipped with four high-speed acquisition cameras, all of which are electrically connected to the FPGA controller (4) to receive the synchronous trigger signal from the FPGA controller (4) and realize independent trigger acquisition or multi-camera synchronous trigger acquisition. The FPGA controller (4) is the core of timing control and data processing of the measuring device.

2. The structured light measurement device with variable magnification and variable field of view according to claim 1, characterized in that, The structured light projector group includes: a first structured light projector (11), a second structured light projector (12), a third structured light projector (13), and a fourth structured light projector (14); the four structured light projectors are symmetrically distributed in a ring around the periphery of the multi-magnification telecentric lens (3), and the projection optical axes of all projectors are directed toward the measurement station of the object to be measured.

3. The structured light measurement device with variable magnification and variable field of view according to claim 1, characterized in that, The internal structure of the multi-magnification telecentric lens (3) includes a lens barrel, a telecentric objective lens group arranged sequentially from the object side to the image side along the main imaging optical axis, and a beam splitting optical path assembly.

4. The structured light measurement device with variable magnification and variable field of view according to claim 3, characterized in that, The beam splitting optical path assembly includes a first beam splitter (31), a second beam splitter (32), and a third beam splitter (33). The three beam splitters are arranged coaxially along the main imaging optical axis to split the incident light reflected from the object under test into four imaging optical paths with equal optical paths, and the four imaging optical paths correspond to four different fixed optical magnifications.

5. The structured light measurement device with variable magnification and variable field of view according to claim 4, characterized in that, Four fixed optical magnifications increase sequentially from the object side to the image side along the main imaging optical axis, corresponding to sequentially decreasing imaging field of view and sequentially increasing theoretical measurement accuracy, thus integrating a multi-magnification optical path through a single lens.

6. The structured light measurement device with variable magnification and variable field of view according to claim 5, characterized in that, The high-speed acquisition camera group includes: a first high-speed acquisition camera (21), a second high-speed acquisition camera (22), a third high-speed acquisition camera (23), and a fourth high-speed acquisition camera (24); the four high-speed acquisition cameras are fixedly connected to the four imaging optical paths of the multi-magnification telecentric lens (3) through a standard C-type interface.

7. The structured light measurement device with variable magnification and variable field of view according to claim 6, characterized in that, In terms of optical transmission, the light reflected by the object under test is collimated by the telecentric objective lens group in the multi-magnification telecentric lens (3), and then reflected by the first beam splitter (31) to the photosensitive chip of the first high-speed acquisition camera (21), reflected by the second beam splitter (32) to the photosensitive chip of the second high-speed acquisition camera (22), reflected by the third beam splitter (33) to the photosensitive chip of the third high-speed acquisition camera (23), and finally the transmitted light is directly incident on the photosensitive chip of the fourth high-speed acquisition camera (24), thus completing the synchronous imaging of four different magnifications.

8. A structured light measurement method with variable magnification and variable field of view, characterized in that, An FPGA controller applied to the structured light measurement device with variable magnification field of view as described in any one of claims 1-7 includes: Step S10: Calibrate the inherent hardware parameters of the structured light measurement device and save them to the on-chip non-volatile memory of the FPGA controller; Step S20: Receive the measurement request for the object under test from the host computer and analyze the geometric features of the object under test; Step S30: Retrieve the fixed inherent hardware parameters, execute the magnification-field of view-accuracy linkage matching algorithm, and output the optimal measurement scheme according to the measurement requirements and geometric features of the object under test; Step S40: Based on the optimal measurement scheme output, perform linkage control on the structured light measurement device to acquire the deformed stripe image after height modulation of the object under test; Step S50: Perform phase calculation and three-dimensional coordinate transformation on the acquired deformed stripe image, and output the final three-dimensional point cloud model.

9. A computer storage medium, characterized in that, include: At least one memory and at least one processor; Memory, used to store one or more program instructions; A processor for running one or more program instructions to perform a structured light measurement method with variable magnification and field of view as described in claim 8.

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