Non-contact measurement method and device for caster bearing compression springback deformation

Abstract

The present application relates to the technical field of caster measuring, in particular to a non-contact measurement method and device for the compression and rebound deformation of a caster, which comprises the following steps: a light projector projects light stripes on the caster in an unloaded state and a loaded compression state to generate first reference data and second reference data, and performs point-by-point difference and extracts deformation to generate a compression deformation index; a sequence of stripe images of the caster in a rebound process after unloading is collected to generate third reference data, which is subjected to point-by-point difference with the first reference data to extract deformation and generate a rebound comprehensive index; a lag ratio calculation is performed on the compression deformation index and the rebound comprehensive index to generate a residual deformation signal, and a difference ratio calculation is performed on the residual deformation signal and the compression deformation index to obtain a measurement result. The present application realizes non-contact and real-time measurement of the micro deformation of the caster in the whole process of heavy load compression and unloading rebound, and solves the technical problems of poor repeatability, easy interference and inability to quantify long-term performance in the prior art.

Description

Technical Field

[0001] This invention relates to the field of caster measurement technology, and more specifically, to a non-contact measurement method and apparatus for caster load compression and springback deformation. Background Technology

[0002] Casters are moving parts used in industrial equipment, medical devices, logistics equipment, and other fields. Their resilience after being compressed determines the product's service life, safety, and operational stability. Under heavy-duty conditions, the caster's wheel body, polyurethane / rubber wheel surface, and elastic support will undergo elastic deformation and residual plastic deformation due to repeated compression. If the residual deformation accumulates too much, it will lead to a decrease in wheel height, lateral bulging, increased rolling resistance, and even safety hazards such as equipment tilting or tipping over.

[0003] In existing technologies, the measurement of compression rebound deformation of casters generally adopts contact measurement methods. Existing methods include direct pressure testing with dial indicators / displacement sensors, and methods using a dedicated compression test bench with a contact extensometer. These methods typically fix the caster to a loading platform, apply a specified load via hydraulic pressure or a servo motor, and place one or more contact displacement sensors on the top of the axle or bracket to calculate the rebound rate or residual deformation ratio. However, because the probe or sensor must maintain continuous physical contact with the caster surface during the measurement process, the measurement results are significantly affected by various interference factors such as contact pressure, contact point position deviation, surface friction, and local stress concentration of the measured object. This results in low measurement accuracy and poor repeatability, especially when measuring small residual deformations (typically in the range of 0.05~0.3mm), where the error often exceeds 20%, failing to meet the deformation measurement accuracy requirements of casters (such as medical precision casters).

[0004] Therefore, a completely new non-contact measurement technology is urgently needed to solve the existing technical bottlenecks. Summary of the Invention

[0005] The main objective of this invention is to provide a non-contact measurement method and device for measuring the compression and rebound deformation of casters, aiming to overcome the technical problem that the measurement results of existing casters are subject to various interference factors during contact measurement, resulting in low measurement accuracy.

[0006] To address the aforementioned problems, this invention proposes a non-contact method for measuring the compression and springback deformation of casters under load, the method comprising: The light projector projects light stripes onto the caster in both the unloaded and loaded / compressed states, and generates first and second reference data based on the light stripe images. The first reference data and the second reference data are differentially analyzed point by point, and the deformation is extracted to generate the compression deformation index. Collect stripe image sequence of the caster rebound process after unloading and generate third reference data. Perform point-by-point difference between the third reference data and the first reference data and extract the deformation amount to generate a comprehensive rebound index. The residual deformation signal is generated by calculating the hysteresis ratio of the compression deformation index and the springback composite index. The difference ratio between the residual deformation signal and the compression deformation index is calculated to obtain the measurement result.

[0007] Further, the step of generating first reference data based on the light stripe image projected by the light projector onto the caster in an unloaded state includes: An initial stripe image is obtained by projecting dual-wavelength light stripes onto the surface of the caster using a light projector. The phase of the two channels of the initial stripe image is calculated to generate a first phase image. The first phase map is unified into a coordinate system based on the preset mapping relationship between phase and height to generate the first reference data.

[0008] Further, the step of generating second reference data based on the light stripe image projected by the light projector onto the caster under compression includes: After the caster bears a preset load and is stably compressed, a compression stripe image is obtained by projecting dual-wavelength light stripes onto the surface of the caster using a light projector. The two channels of the compressed stripe image are phase-calculated to generate a second phase map. The second phase map is then unified into a coordinate system based on the coordinate system of the first reference data to generate the second reference data.

[0009] Further, the step of performing point-by-point difference between the first reference data and the second reference data and extracting the deformation to generate the compression deformation index includes: Perform point-by-point height difference calculation on the first and second reference data to obtain compressed height data; The region with the smallest deformation and the highest continuity in the compression height data is set as the reference plane, and the axial displacement components of all points on the reference plane are averaged to obtain the subsidence. Based on the compression height data, multiple vertical sections are extracted along the wheel axle centerline and the maximum lateral outward expansion of the wheel body is calculated to obtain the lateral bulging deformation. The subsidence and lateral bulging deformation are fused according to a preset weight ratio to obtain the compression deformation index.

[0010] Furthermore, the step of acquiring the stripe image sequence of the caster's rebound process after unloading and generating third reference data, performing point-by-point difference between the third reference data and the first reference data and extracting the deformation amount to generate a rebound composite index, further includes: A sequence of rebound stripe images is obtained by continuously projecting dual-wavelength light stripes onto the surface of the unloaded caster using a light projector. Phase calculation is performed on each frame of the dual-channel image of the rebound stripe image sequence and unified to the coordinate system of the first reference data to obtain the rebound point cloud sequence. The point cloud of each frame of the rebound point cloud sequence is differentially analyzed with the first reference data point by point, and deformation features are extracted to obtain the rebound deformation sequence. The rebound deformation sequence is integrated in chronological order starting from the moment of unloading to obtain the comprehensive rebound index.

[0011] Further, the step of calculating the residual deformation signal by performing a hysteresis ratio calculation on the compression deformation index and the springback composite index includes: The compression deformation index is set as the amplitude benchmark, and the springback composite index is scaled proportionally so that the springback composite index value at the moment of unloading is equal to the compression deformation index, thus obtaining the springback sequence. Curve fitting is performed on the rebound sequence to generate a steady state moment. The difference between the actual deformation amount corresponding to the steady state moment and the preset rebound amount is divided by the compression deformation index to obtain the rebound hysteresis ratio. The residual deformation signal is obtained by multiplying the compression deformation index, the springback hysteresis ratio, and a preset empirical correction constant.

[0012] Further, the step of calculating the difference ratio between the residual deformation signal and the compressive deformation index to obtain the measurement result includes: The absolute residual deformation is obtained by subtracting the residual deformation signal from the compression deformation index and taking the absolute value. The residual deformation ratio is obtained by dividing the absolute residual deformation by the compression deformation index. The residual deformation ratio is compared sequentially with multiple preset thresholds, and the corresponding bearing capacity level is determined based on the interval corresponding to the calculation result to obtain the measurement result.

[0013] The present invention also proposes a non-contact measuring device for the compression and springback deformation of a caster under load, comprising: The acquisition module is used to project light stripes onto the caster in the unloaded state and the loaded and compressed state according to the light projector, and to generate first reference data and second reference data based on the light stripe images; The extraction module is used to perform point-by-point difference between the first reference data and the second reference data and extract the deformation amount to generate the compression deformation index. The calculation module is used to collect stripe image sequences of the caster's rebound process after unloading and generate third reference data. The third reference data is then differentially analyzed with the first reference data point by point, and the deformation is extracted to generate a comprehensive rebound index. The generation module is used to calculate the hysteresis ratio of the compression deformation index and the springback composite index to generate a residual deformation signal, and to calculate the difference ratio between the residual deformation signal and the compression deformation index to obtain the measurement result.

[0014] The present invention also proposes a computer device comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described method.

[0015] The present invention also proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described method.

[0016] Compared with the prior art, this application has the following beneficial effects: This application proposes a non-contact measurement method and device for caster load compression and rebound deformation. By establishing a multi-frame three-dimensional data chain of unloaded, loaded compression, and rebound processes under a unified coordinate system, it realizes compression deformation extraction, lateral bulging fusion, and rebound sequence processing. The global compression and lateral bulging are weighted to generate a comprehensive compression deformation index. By coupling the rebound hysteresis ratio with the time-domain amplitude of the residual deformation prediction signal, the permanent residual deformation of the caster after long-term use can be accurately predicted. This overcomes the shortcomings of existing technologies that can only measure after the fact and cannot provide early warning. The load-bearing performance evaluation index is calculated by the difference ratio between the residual deformation prediction signal and the compression characteristic signal. The entire measurement process does not require sensor contact, effectively solving the technical problems of poor repeatability, susceptibility to interference, and inability to quantify long-term performance in existing technologies. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0019] Figure 1 This is a schematic diagram of the steps of a non-contact measurement method for the compression and springback deformation of a caster under load, according to an embodiment of the present invention. Figure 2 This is a schematic block diagram of a non-contact measuring device for measuring the compression and rebound deformation of a caster according to an embodiment of the present invention; Figure 3 This is a schematic block diagram of the structure of a computer device according to an embodiment of the present invention; The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of features, integers, steps, operations, elements, modules, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, modules, components, and / or groups thereof. It should be understood that when an element is referred to as “connected” or “coupled” to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein may include wireless connection or wireless coupling. The term “and / or” as used herein includes all or any modules and all combinations of one or more associated listed items.

[0022] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0023] Reference Figure 1 This invention provides a non-contact method for measuring the compression and rebound deformation of casters under load, comprising the following steps: S1: Project light stripes onto the caster in both unloaded and loaded / compressed states using a light projector, and generate first and second reference data based on the light stripe images; In step S1, a light projector is fixedly installed directly above the caster. The light projector can be a projector with a lens replaced by a striped slide projecting a fixed striped pattern. Preferably, two line structure light projectors with different wavelengths are used. The first projector emits a red laser stripe with a wavelength of 650nm, and the second projector emits a blue laser stripe with a wavelength of 450nm. A 15° angle is set between the projection planes of the two projectors, so that the red and blue light stripes form a partially overlapping cross-covering area on the caster surface. The use of different wavelengths avoids the phase ambiguity problem caused by monochromatic light stripes on complex curved surfaces. An industrial camera is fixed in front of the projectors. A color filter that can be synchronously switched or a beam splitter is installed in front of the camera lens, allowing the camera to capture both red and blue stripe images simultaneously, or to acquire red and blue images sequentially in a very short time by switching the color filter. The relative positions of the camera and the two projectors remain completely fixed throughout the measurement cycle. When the caster is in a completely unloaded initial free state, the light projector is activated to simultaneously project red and blue structured light stripes onto the caster surface, and the camera simultaneously acquires images of the deformed stripes on the caster surface. The acquired raw stripe images are then separated into red and blue channels, yielding pure red and pure blue stripe images respectively. Phase calculation is performed independently on these two sub-images using a phase-shifting and grayscale encoding hybrid algorithm. First, the wrapping phase of each stripe (range -π to π) is calculated, and then phase unwrapping is performed with the aid of grayscale encoding to obtain a continuous absolute phase map. Using pre-calibrated system parameters (projector light plane equation, camera intrinsic and extrinsic parameters), the red and blue absolute phase maps are converted into two sets of three-dimensional point cloud data using the principle of triangulation. Since the red and blue point clouds come from the same frame and the same coordinate system, they are rigidly registered and fused into a complete three-dimensional point cloud, i.e., the first reference data, which includes the three-dimensional coordinates of the caster body, polyurethane / rubber wheel surface, metal bracket, and axle.

[0024] After completing the measurement in the unloaded state, keeping the projector and camera positions and all parameters completely unchanged, a standard load (e.g., 500kg or 1000kg vertical load) is applied under the caster, causing significant compression of the caster's rubber surface, slight tilting of the support, and outward bulging of the wheel sidewalls. At this time, the dual-light projector continues to project red and blue structured light stripes at the exact same power, frequency, and angle as in the unloaded state, while the camera synchronously acquires images of the deformed stripes under the loaded compression state at the same frame rate and exposure parameters. Similarly, red and blue channel separation and phase-to-3D coordinate conversion, as well as cross-verification and stitching of the red and blue dual-channel point clouds, are performed to generate a complete 3D point cloud under the loaded compression state, i.e., the second reference data. Since the projector and camera did not move during the two measurements, the two data sets are perfectly aligned in the same coordinate system, and the correspondence between the two sets of point clouds is a natural point-to-point correspondence, eliminating the need for ICP or other point cloud registration algorithms. The first reference data P0 includes the original stress-free state of the caster, and the second reference data P1 includes the instantaneous compression deformation state of the caster under a specific load.

[0025] S2: Perform point-by-point difference between the first reference data and the second reference data and extract the deformation to generate the compression deformation index; In step S2, point-by-point subtraction involves performing point-to-point subtraction between the point cloud of P1 and the point cloud of P0 in the same coordinate system. Since the generation process of the two point clouds is the same and the camera parameters remain unchanged, each spatial point in the point cloud can be matched. Therefore, for any point coordinate (x0, y0, z0) in P0 and the corresponding point coordinate (x1, y1, z1) in P1, the three-dimensional displacement vectors are calculated as Δx = x1-x0, Δy = y1-y0, and Δz = z1-z0, thus obtaining a compression deformation array V. compress Each vector in the compression deformation array represents the displacement direction and magnitude of that point from unloaded to loaded compression state. The compression deformation array represents the overall deformation distribution of the caster, including axial compression, radial expansion, and possible torsional deformation. Deformation is extracted from this compression deformation array to generate the compression deformation index. The extraction process is achieved by automatically identifying feature regions and calculating representative deformation in specific directions. Specifically, the top plane region of the caster bracket is automatically identified as a reference surface in the compression deformation array. This reference surface is a flat region extracted from P0 or P1 using a point cloud segmentation algorithm (such as plane fitting based on normal vector clustering). It can be the upper surface of the bracket, which mainly exhibits overall sinking rather than local deformation during loading. The overall sinking of this reference surface is calculated as the global compression ΔH. The specific calculation method is to take the average height z0 of the reference surface in P0. avg (Average z-coordinate along the direction of gravity) and average height z1 in P1 avg Then ΔH = z0 avg -z1avg A positive value of ΔH represents the compression settlement amplitude in millimeters, indicating the main axial compression deformation borne by the caster. Multiple vertical sections are taken along the wheel axle centerline, which is the caster's rotation axis determined from the P0 point cloud through cylindrical fitting or spindle extraction. Five to ten equally spaced vertical sections can be taken, each a two-dimensional profile curve. The maximum outward expansion of the wheel's outer contour at each section is extracted from the compression deformation array; that is, the maximum positive displacement (bulging direction) from the P0 contour to the P1 contour is calculated in the radial direction. For each section, the maximum radial displacement of all contour points is taken as the maximum outward expansion ΔR of that section. i Finally, the average of the maximum outward expansion of all cross sections is taken as the lateral bulge. , where n is the number of cross sections, and ΔR quantifies the lateral expansion of the wheel sidewall caused by structural buckling. The global compression ΔH and the lateral bulging ΔR are weighted and fused to generate the compression deformation index S. compress The specific calculation method is S compress = (7*ΔH + 3*ΔR) / 10, the weighting ratio of 7:3 is because axial compression ΔH corresponds to load-bearing capacity and comfort, accounting for more than 70% of the deformation effect, while lateral bulging ΔR is mainly an auxiliary effect, affecting wheel stability but contributing little to the overall load-bearing stiffness. The 7:3 weighting ratio can make S compress The correlation with the equivalent stiffness coefficient of the caster reaches over 0.95. To avoid overfitting lateral noise, a weighting ratio of 5:5 amplifies bulging fluctuations, leading to instability of the index under low loads. An 8:2 ratio ignores significant lateral bulging in highly elastic materials. Therefore, 7:3 is the optimal empirical ratio to balance axial dominance and lateral compensation, making S... compress As a single scalar, it has higher uniqueness and comparability in its representation.

[0026] S3: Collect stripe image sequence of the caster rebound process after unloading and generate third reference data. Perform point-by-point difference between the third reference data and the first reference data and extract the deformation amount to generate a comprehensive rebound index. In step S3, the loading device is unloaded, and the industrial camera continues to maintain the same acquisition parameters as in steps S1 and S2. A light projector with the same parameters continuously and synchronously acquires a sequence of red and blue dual-channel deformed stripe images of the caster surface after unloading. Each frame of the stripe image is processed using the same real-time phase resolution method as in steps S1 and S2, ensuring that the 3D point cloud generated during the rebound process is in the same coordinate system as the first reference point cloud P0 generated in step S1, thus generating the complete 3D point cloud P at that moment. t (t=1, 2, ..., N, N≥300 frames), the instantaneous 3D point cloud sequence {P} of the rebound is obtained in chronological order throughout the entire rebound process. t}, that is, the third reference data. For each frame of point cloud P in the third reference data t Each time step performs the same point-by-point difference operation as the first reference data to obtain the rebound deformation array V at each time step. rebound (t) = P t –P0 (vector subtraction) yields the displacement components of each spatial point in the X, Y, and Z directions after differencing. For each frame's V... rebound (t) Repeat the same feature extraction process as step S2, automatically identify the top plane of the support as the reference plane, and calculate the overall subsidence (i.e., the remaining compression) ΔH(t) of this plane relative to P0; then take 8 to 12 vertical sections along the wheel axle centerline, extract the maximum outward expansion of the wheel body contour of each section, and take the average to obtain the lateral remaining bulge ΔR(t); finally, weight and fuse ΔH(t) and ΔR(t) with a weight of 7:3 to obtain the instantaneous remaining deformation comprehensive index S at this moment. t =0.7*ΔH(t) + 0.3*ΔR(t). As time t increases from the instant of unloading (t≈0, at which point S0≈S...),... compress After reaching a final stable state (1.5–3 seconds later), the rebound composite index sequence {S} is obtained, which monotonically decreases over time. t} (t=1, 2, ..., N), the starting point of this sequence is close to the compressibility exponent S generated in step S2. compress The endpoint approaches the stable value S. ∞ S ∞ This represents the final residual permanent deformation; the springback composite index is the sum of the values ​​of the entire dynamic sequence {S}. t}

[0027] S4: Calculate the residual deformation signal by performing a hysteresis ratio calculation on the compression deformation index and the springback composite index, and calculate the difference ratio between the residual deformation signal and the compression deformation index to obtain the measurement result.

[0028] In step S4, the instantaneous residual deformation comprehensive index S is... t Perform a single exponential decay fitting, that is, fit the function form S using the least squares method. fit (t) = S res +(S compress -S res )*e (-t / τ) S res The long-term residual exponent is obtained from the fitting, and τ is the rebound time constant (between 0.3 and 2.0 seconds). Calculate the theoretical pure elastic rebound final value S. theoretical = 0 (a purely elastic material should completely return to its unloaded state after unloading). Then find the moment t when the rebound process reaches 95% of its steady state. 95% That is, when |S t -S res| / |S compress -S res The earliest time point corresponding to | ≤ 0.05. At this moment, the actual residual deformation index is S. t95% In theory, a purely elastic material would have already returned to zero by this point, but in reality, the material still retains some deformation. Therefore, the springback hysteresis ratio R is defined as follows: lag = ( S t95% -0) / S compress = S t95% / S compress In the stage where springback is basically complete (95%), the percentage of deformation that remains and cannot be reversed indicates irreversible behavior caused by internal viscoelasticity, microplastic damage, or molecular chain rearrangement. lag The range is between 0.02 and 0.25; a higher value indicates greater material plasticity. This yields R. lag Then, the difference ratio between the residual deformation signal and the compressive deformation index is calculated. The residual deformation signal refers to the initially predicted residual deformation amount D. reaw = S compress *R lag The proportion of the total deformation generated by the current loading that is destined not to spring back is extracted to form a preliminary residual deformation prediction value. The residual deformation is then corrected using an empirical correction constant K=1.05, and the residual deformation prediction signal D is obtained. res = S compress * R lag * 1.05. D res With S compress By calculating the difference ratio, the dimensionless load-bearing performance evaluation index Q = (S compress- D res ) / S compress = 1-R lag * 1.05. Since K=1.05 is a fixed empirical value, Q is actually equivalent to 1-1.05*R. lag The closer the Q value of this index is to 1, the better the material can rebound even after considering the most conservative plasticity accumulation amplification, indicating excellent elastic properties. Conversely, a smaller Q value indicates a higher proportion of plasticity, making the material more prone to permanent deformation. The threshold standard is set according to industry standards. For example, it is set as follows: when Q ≥ 0.97, the output is excellent; when 0.95 ≤ Q < 0.97, the output is good; when 0.92 ≤ Q < 0.95, the output is acceptable; and when Q < 0.92, the output is unacceptable. The original compression index S is then adjusted. compress Complete springback curve, predicted residual deformation D res The measurement result is obtained by combining the evaluation index Q.

[0029] In one embodiment, the step of generating first reference data based on the light stripe image generated by projecting light stripes onto the caster in an unloaded state using a light projector includes: An initial stripe image is obtained by projecting dual-wavelength light stripes onto the surface of the caster using a light projector. The phase of the two channels of the initial stripe image is calculated to generate a first phase image. The first phase map is unified into a coordinate system based on the preset mapping relationship between phase and height to generate the first reference data.

[0030] In the above embodiment, with the caster completely unloaded and without any external force, two structured light projectors with different wavelengths (650nm red light and 450nm blue light) are fixed at a 15° angle approximately 800mm directly above the caster, simultaneously projecting sinusoidally distributed dual-wavelength light stripes. After an industrial camera synchronously acquires a single frame image, two independent stripe patterns Φ for the red and blue channels are separated using a hardware color filter. red and Φ blue Phase-shifting phase calculations were performed independently on the red and blue channel fringes to obtain two sets of wrapped phase maps, one for red and one for blue. These were then phase-unfolded to obtain continuous absolute phase maps. Using a pre-calibrated phase-to-height mapping relationship H = k*ΔΦ+C (where k is a system structural parameter and C is a constant offset, obtained through multiple calibrations of a standard plane at different heights using least-squares fitting with a calibration accuracy of 0.01 mm), the two sets of absolute phase maps were uniformly transformed to the same coordinate system and fused to generate the first reference data, namely the unsupported 3D point cloud P0.

[0031] In one embodiment, the step of projecting light stripes onto the caster under compression conditions using a light projector and generating second reference data based on the light stripe image includes: After the caster bears a preset load and is stably compressed, a compression stripe image is obtained by projecting dual-wavelength light stripes onto the surface of the caster using a light projector. The two channels of the compressed stripe image are phase-calculated to generate a second phase map. The second phase map is then unified into a coordinate system based on the coordinate system of the first reference data to generate the second reference data.

[0032] In the above embodiment, after the caster bears a preset load (which can be 1.2 times the rated load of the caster) on the loading platform and is stably compressed for at least 10 seconds, the projector, camera, and optical path remain completely stationary, and the same dual-wavelength light stripes continue to be projected synchronously. The camera acquires red and blue dual-channel stripe images at the moment of compression. Using the same phase shift and dual-wavelength absolute phase calculation process as described above, the absolute phase map under the load state is obtained. Since the positions of the camera and projector have not changed, the calibrated phase and height mapping relationship H = k*ΔΦ+C is used without recalibration. The absolute phase map under the load state is directly converted to the same coordinate system as the first reference data P0, thereby generating the second reference data, namely the three-dimensional point cloud P1 at the moment of compression.

[0033] In one embodiment, the step of performing point-by-point difference between the first reference data and the second reference data and extracting the deformation to generate a compression deformation index includes: Perform point-by-point height difference calculation on the first and second reference data to obtain compressed height data; The region with the smallest deformation and the highest continuity in the compression height data is set as the reference plane, and the axial displacement components of all points on the reference plane are averaged to obtain the subsidence. Based on the compression height data, multiple vertical sections are extracted along the wheel axle centerline and the maximum lateral outward expansion of the wheel body is calculated to obtain the lateral bulging deformation. The subsidence and lateral bulging deformation are fused according to a preset weight ratio to obtain the compression deformation index.

[0034] In the above embodiment, the first reference data P0 and the second reference data P1 are subjected to point-by-point height difference (calculating the Z-axis direction, i.e., ΔH(x, y) = H1(x, y) - H0(x, y)) to obtain a compression height data map. The flattest and most continuous area at the top of the caster bracket (which can be the upper surface of the bracket) is identified in the compression height data map as a reference plane. The average Z-axis displacement of all points within this plane is taken to obtain the global subsidence ΔH. Simultaneously, taking the wheel axle centerline detected by the caster as the axis, 12 vertical sections are extracted at equal intervals along the axial direction. The maximum radial outward expansion distance is found on the outer contour of the wheel body at each section, and the average of the 12 maximum values ​​is taken as the lateral bulging deformation ΔR. The final compression deformation index S... compress = 0.7*ΔH + 0.3*ΔR, which represents the overall compressive deformation of the caster under this load.

[0035] In one embodiment, the step of acquiring a stripe image sequence of the caster's rebound process after unloading and generating third reference data, performing point-by-point difference analysis between the third reference data and the first reference data and extracting the deformation amount to generate a rebound composite index, further includes: A sequence of rebound stripe images is obtained by continuously projecting dual-wavelength light stripes onto the surface of the unloaded caster using a light projector. Phase calculation is performed on each frame of the dual-channel image of the rebound stripe image sequence and unified to the coordinate system of the first reference data to obtain the rebound point cloud sequence. The point cloud of each frame of the rebound point cloud sequence is differentially analyzed with the first reference data point by point, and deformation features are extracted to obtain the rebound deformation sequence. The rebound deformation sequence is integrated in chronological order starting from the moment of unloading to obtain the comprehensive rebound index.

[0036] In the above embodiment, after the load is completely removed instantaneously, dual-wavelength light stripes are continuously projected through a light projector, and a camera simultaneously acquires a sequence of stripe images of the rebound process. For each frame, dual-wavelength phase calculation and unified coordinate system transformation are repeated to obtain the rebound point cloud sequence P. t (t=1, 2, ... 200+). For each frame P t Using the same point-by-point differencing, reference plane subsidence, and lateral bulging extraction as the first reference data P0, the instantaneous compression deformation index sequence S at each moment is obtained. t (t), the sequence from the moment of unloading Scompress It begins to gradually decay to a stable residual value. Taking the first frame after unloading as time t=0, the entire S... t The sequence is integrated in chronological order to obtain the springback composite index, which represents the dynamic curve of the entire process from maximum compression to final residual deformation.

[0037] In one embodiment, the step of calculating the residual deformation signal by performing a hysteresis ratio calculation on the combined compression and springback indices includes: The compression deformation index is set as the amplitude benchmark, and the springback composite index is scaled proportionally so that the springback composite index value at the moment of unloading is equal to the compression deformation index, thus obtaining the springback sequence. Curve fitting is performed on the rebound sequence to generate a steady state moment. The difference between the actual deformation amount corresponding to the steady state moment and the preset rebound amount is divided by the compression deformation index to obtain the rebound hysteresis ratio. The residual deformation signal is obtained by multiplying the compression deformation index, the springback hysteresis ratio, and a preset empirical correction constant.

[0038] In the above embodiments, the compression deformation index S compress As an absolute amplitude benchmark, the rebound composite index sequence S t Perform a scaling operation so that the value of the scaled sequence at the instant of unloading (t=0) is exactly equal to S. compress The normalized rebound sequence S is obtained. norm (t). For S norm(t) Perform double exponential function fitting S norm (t)=A*e (-t / τ1) +B*e (-t / τ2) +C, coefficient of determination R 2 The steady-state time t is determined when the value is greater than 0.98. stable (Can be within 1.5 to 3 seconds). In t stable The difference between the actual residual deformation at time t and the theoretical perfectly elastic springback (which should be 0) divided by S compress That is, to obtain the rebound hysteresis ratio R lag (Range 0.03~0.25). Residual deformation signal D res = S compress *R lag *1.05, where 1.05 is an empirical correction constant used to compensate for the effects of minute nonlinearity in measurement and material creep hysteresis.

[0039] In one embodiment, the step of calculating the difference ratio between the residual deformation signal and the compressive deformation index to obtain the measurement result includes: The absolute residual deformation is obtained by subtracting the residual deformation signal from the compression deformation index and taking the absolute value. The residual deformation ratio is obtained by dividing the absolute residual deformation by the compression deformation index. The residual deformation ratio is compared sequentially with multiple preset thresholds, and the corresponding bearing capacity level is determined based on the interval corresponding to the calculation result to obtain the measurement result.

[0040] In the above embodiment, the absolute residual deformation |S compress -D res |, then divide by S compress Obtain the residual deformation ratio R residual =|S compress- D res | / S_compress (i.e., 1-Q). The smaller this ratio, the better the rebound performance. The Q value is compared with the preset multi-level standards, and four levels of conclusions are output: excellent, good, qualified, and unqualified. At the same time, a complete test report is generated, which includes the compression deformation index, rebound curve, residual deformation signal, residual deformation ratio, and level.

[0041] Reference Figure 2 A non-contact measuring device for measuring the compression and rebound deformation of a caster wheel, comprising: The acquisition module 100 is used to project light stripes onto the caster in the unloaded state and the loaded and compressed state according to the light projector, and to generate first reference data and second reference data based on the light stripe images. Extraction module 200 is used to perform point-by-point difference between the first reference data and the second reference data and extract the deformation amount to generate a compression deformation index; The calculation module 300 is used to collect the stripe image sequence of the caster rebound process after unloading and generate third reference data. The third reference data is then differentially analyzed with the first reference data point by point, and the deformation is extracted to generate a comprehensive rebound index. The generation module 400 is used to calculate the hysteresis ratio of the compression deformation index and the springback composite index to generate a residual deformation signal, and to calculate the difference ratio between the residual deformation signal and the compression deformation index to obtain the measurement result.

[0042] Reference Figure 3 This application also provides a computer device, which may be a server, and its internal structure may be as follows: Figure 3 As shown, the computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and database. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores database data. The network interface is used for communication with external terminals via a network connection. When executed by the processor, the computer program implements a non-contact measurement method for caster load compression and springback deformation.

[0043] One embodiment of this application also provides a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements a non-contact measurement method for the compression and rebound deformation of a caster under load, comprising the following steps: projecting light stripes onto the caster in an unloaded state and a loaded compression state using a light projector; generating first reference data and second reference data based on the light stripe images; performing point-by-point difference between the first reference data and the second reference data and extracting the deformation amount to generate a compression deformation index; acquiring a stripe image sequence of the caster's rebound process after unloading and generating third reference data; performing point-by-point difference between the third reference data and the first reference data and extracting the deformation amount to generate a rebound composite index; calculating the hysteresis ratio of the compression deformation index and the rebound composite index to generate a residual deformation signal; and calculating the difference ratio between the residual deformation signal and the compression deformation index to obtain a measurement result.

[0044] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media provided in this application and used in the embodiments can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual-speed SDRAM (SSRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0045] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A non-contact measurement method for the compression and springback deformation of a caster under load, characterized in that, include: The light projector projects light stripes onto the caster in both the unloaded and loaded / compressed states, and generates first and second reference data based on the light stripe images. The first reference data and the second reference data are differentially analyzed point by point, and the deformation is extracted to generate the compression deformation index. Collect stripe image sequence of the caster rebound process after unloading and generate third reference data. Perform point-by-point difference between the third reference data and the first reference data and extract the deformation amount to generate a comprehensive rebound index. The residual deformation signal is generated by calculating the hysteresis ratio of the compression deformation index and the springback composite index. The difference ratio between the residual deformation signal and the compression deformation index is calculated to obtain the measurement result.

2. The non-contact measurement method for the compression and springback deformation of a caster under load according to claim 1, characterized in that, The steps of generating first reference data based on the light stripe image projected by the light projector onto the caster in an unloaded state include: An initial stripe image is obtained by projecting dual-wavelength light stripes onto the surface of the caster using a light projector. The phase of the two channels of the initial stripe image is calculated to generate a first phase image. The first phase map is unified into a coordinate system based on the preset mapping relationship between phase and height to generate the first reference data.

3. The non-contact measurement method for the compression and springback deformation of a caster under load according to claim 1, characterized in that, The step of generating second reference data based on the light stripe image, which projects light stripes onto the caster under compression conditions using a light projector, includes: After the caster bears a preset load and is stably compressed, a compression stripe image is obtained by projecting dual-wavelength light stripes onto the surface of the caster using a light projector. The two channels of the compressed stripe image are phase-calculated to generate a second phase map. The second phase map is then unified into a coordinate system based on the coordinate system of the first reference data to generate the second reference data.

4. The non-contact measurement method for the compression and springback deformation of a caster under load according to claim 1, characterized in that, The step of performing point-by-point difference between the first reference data and the second reference data and extracting the deformation to generate the compression deformation index includes: Perform point-by-point height difference calculation on the first and second reference data to obtain compressed height data; The region with the smallest deformation and the highest continuity in the compression height data is set as the reference plane, and the axial displacement components of all points on the reference plane are averaged to obtain the subsidence. Based on the compression height data, multiple vertical sections are extracted along the wheel axle centerline and the maximum lateral outward expansion of the wheel body is calculated to obtain the lateral bulging deformation. The subsidence and lateral bulging deformation are fused according to a preset weight ratio to obtain the compression deformation index.

5. The non-contact measurement method for the compression and springback deformation of a caster under load according to claim 4, characterized in that, The steps of acquiring stripe image sequences of the caster's rebound process after unloading and generating third reference data, performing point-by-point difference analysis between the third reference data and the first reference data, extracting the deformation amount, and generating a comprehensive rebound index further include: A sequence of rebound stripe images is obtained by continuously projecting dual-wavelength light stripes onto the surface of the unloaded caster using a light projector. Phase calculation is performed on each frame of the dual-channel image of the rebound stripe image sequence and unified to the coordinate system of the first reference data to obtain the rebound point cloud sequence. The point cloud of each frame of the rebound point cloud sequence is differentially analyzed with the first reference data point by point, and deformation features are extracted to obtain the rebound deformation sequence. The rebound deformation sequence is integrated in chronological order starting from the moment of unloading to obtain the comprehensive rebound index.

6. The non-contact measurement method for the compression and springback deformation of a caster under load according to claim 1, characterized in that, The step of calculating the residual deformation signal by performing hysteresis ratio calculation on the combined compression and springback indices includes: The compression deformation index is set as the amplitude benchmark, and the springback composite index is scaled proportionally so that the springback composite index value at the moment of unloading is equal to the compression deformation index, thus obtaining the springback sequence. Curve fitting is performed on the rebound sequence to generate a steady state moment. The difference between the actual deformation amount corresponding to the steady state moment and the preset rebound amount is divided by the compression deformation index to obtain the rebound hysteresis ratio. The residual deformation signal is obtained by multiplying the compression deformation index, the springback hysteresis ratio, and a preset empirical correction constant.

7. The non-contact measurement method for the compression and springback deformation of a caster under load according to claim 1, characterized in that, The step of calculating the difference ratio between the residual deformation signal and the compressive deformation index to obtain the measurement result includes: The absolute residual deformation is obtained by subtracting the residual deformation signal from the compression deformation index and taking the absolute value. The residual deformation ratio is obtained by dividing the absolute residual deformation by the compression deformation index. The residual deformation ratio is compared sequentially with multiple preset thresholds, and the corresponding bearing capacity level is determined based on the interval corresponding to the calculation result to obtain the measurement result.

8. A non-contact measuring device for measuring the compression and springback deformation of a caster, characterized in that, include: The acquisition module is used to project light stripes onto the caster in the unloaded state and the loaded and compressed state according to the light projector, and to generate first reference data and second reference data based on the light stripe images; The extraction module is used to perform point-by-point difference between the first reference data and the second reference data and extract the deformation amount to generate the compression deformation index. The calculation module is used to collect stripe image sequences of the caster's rebound process after unloading and generate third reference data. The third reference data is then differentially analyzed with the first reference data point by point, and the deformation is extracted to generate a comprehensive rebound index. The generation module is used to calculate the hysteresis ratio of the compression deformation index and the springback composite index to generate a residual deformation signal, and to calculate the difference ratio between the residual deformation signal and the compression deformation index to obtain the measurement result.

9. A computer device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 7.

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