A double-layer exchange platform gantry marking control method and system

Abstract

This invention specifically provides a gantry marking control method and system for a double-layer exchange platform, comprising: after the platform is exchanged into position, controlling the gantry to drive the rangefinder to scan along the material-free reference area of ​​the rack structure, extracting the periodic features of the height sequence to determine the measured tooth pitch, comparing it with the pre-stored upper and lower platform templates to determine the identity of the currently positioned platform; determining the reference height based on the platform identity and the measured statistics of the first height sequence, sampling the second height sequence of the plate area and calculating the residual, attributing the residual spatial distribution pattern to distinguish between plate warping, slag adhesion, and platform deformation; and selecting the corresponding coordinate compensation strategy and focusing strategy to perform marking based on the attribution results. This invention requires no additional vision or point cloud sensors and can automatically complete platform identification, dynamic reference correction, and working condition adaptation control after platform exchange, adapting to the complex working conditions and cycle constraints of thick plate cutting production lines.

Description

Technical Field

[0001] This invention belongs to the field of laser cutting composite processing equipment control technology, specifically relating to a double-layer exchange platform gantry marking control method and system. Background Technology

[0002] In laser cutting composite processing equipment, a double-layer exchange platform handles the reciprocating transport of the sheet metal between the main cutting station and the external gantry marking station. Unlike single-station laser marking machines, the workpiece in this scenario is not stationary: the platform moves in and out of the working area along guide rails. Each exchange may introduce mechanical backlash, rack deformation, incomplete release of pneumatic clamps, and platform settlement, causing the marking reference surface itself to drift with the exchange action. Simultaneously, after the main machine completes the thick plate cutting, the sheet metal enters the marking station, and its surface often contains cutting slag, thermal deformation warping, kerf, and residual material. The "height jump" observed by the rangefinder during edge inspection could be any of the actual boundary, slag, or the platform rack's periodic structure. Furthermore, the marking gantry is located to the side of the main cutting machine, prohibiting the installation of additional sensors such as CCDs, structured light sensors, or contact probes, as these would obstruct the cutting light path or cause contamination from splashes. Existing marking and focusing solutions rely on the premise of "workpiece stationary, table fixed, and factory-calibrated zero plane as the reference." Using only height thresholds for judgment fails to simultaneously distinguish platform identity, platform deformation, sheet warping, and slag adhesion in exchange platform scenarios, leading to incorrect marking parameter calls, focus deviations, and unintended machine shutdowns. Therefore, a dedicated control method is needed that can perform platform status verification and sheet condition attribution after platform exchange, relying solely on a single-point laser rangefinder and the gantry's own motion axis. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the prior art, the present invention provides a gantry marking control method and system for a two-layer exchange platform to solve the above-mentioned technical problems.

[0004] In a first aspect, the present invention provides a gantry marking control method for a double-layer exchange platform. The double-layer exchange platform includes an upper platform and a lower platform that can alternately enter the gantry marking station. The support surfaces of both the upper and lower platforms have a periodic rack and pinion structure. A single-point laser rangefinder is provided on the gantry marking station, comprising: After the platform is in place, the gantry is controlled to drive the single-point laser rangefinder to scan along the material-free reference area of ​​the rack structure, collect the first height sequence, extract the periodic features of the first height sequence, and determine the measured tooth pitch based on the periodic features. The measured tooth pitch is compared with the pre-stored upper platform template and lower platform template respectively, and the identity of the currently positioned platform is determined based on the comparison results; Based on the identity of the current platform and the measured statistics of the first height sequence, a reference height is determined. The second height sequence is sampled in the plate area using the single-point laser rangefinder, and the residual of the second height sequence is calculated. The residual is attributed according to the spatial distribution pattern of the residual to distinguish between plate warping, slag adhesion, and platform deformation. Based on the attribution results, select the corresponding coordinate compensation strategy and focus strategy to perform the labeling.

[0005] In an optional implementation, extracting the periodic features of the first height sequence and determining the measured tooth pitch based on the periodic features includes: Perform autocorrelation analysis or peak detection on the first height sequence to extract the tooth tip position sequence and tooth valley position sequence; The average difference between adjacent tooth tip positions is used as the measured tooth pitch, and the average tooth tip height and average tooth valley height are statistically analyzed.

[0006] In an optional implementation, the step of comparing the measured tooth pitch with pre-stored upper platform templates and lower platform templates, and determining the identity of the currently positioned platform based on the comparison results, includes: When the deviation between the measured tooth pitch and the tooth pitch of a certain platform template is within the tolerance range, and the average tooth tip height and the average tooth valley height both fall within the corresponding range of the platform template, the currently positioned platform is determined to be the platform corresponding to the template. When the deviation between the measured tooth pitch and the tooth pitch of the two platform templates exceeds the tolerance range, or when the correlation of the periodic feature is lower than the preset threshold, it is determined that the platform is not in place or the rack structure is abnormal, and an alarm signal is output.

[0007] In an optional implementation, determining the reference height based on the identity of the currently arriving platform and the measured statistics of the first height sequence includes: Calculate the standard deviation of the tooth tip height sequence, the standard deviation of the tooth valley height sequence, and the overall offset of the comprehensive height value calculated from the mean tooth tip height and the mean tooth valley height relative to the corresponding platform template; When both the standard deviation of the tooth tip height and the standard deviation of the tooth valley height are less than the first threshold, and the overall offset is less than the second threshold, the overall value is used as the reference height. When the overall offset is greater than or equal to the second threshold and less than the third threshold, the reference height is taken as the platform template plus the overall offset, and the platform deformation position is recorded. When the overall offset is greater than or equal to the third threshold, the platform deformation is determined to be out of tolerance, marking is prohibited and an alarm signal is output.

[0008] In an optional implementation, sampling the second height sequence of the plate area using the single-point laser rangefinder includes: Based on the reference height, the lower threshold of the candidate points of the board is set as the sum of the reference height and the minimum board thickness, and the upper threshold is the sum of the reference height, the maximum board thickness and the slag tolerance. The gantry is controlled to drive the single-point laser rangefinder to travel along a preset edge-following trajectory above the board area. The height value of each sampling point is collected at a preset sampling interval. Sampling points whose height values ​​fall between the lower threshold and the upper threshold are marked as candidate points of the board, forming the second height sequence.

[0009] In an optional implementation, attributing the residuals based on their spatial distribution patterns to distinguish between plate warping, slag adhesion, and plateau deformation includes: Calculate the overall systematic offset of the residual, compare the overall systematic offset with the overall offset of the first height sequence, and if they are consistent, attribute it to platform deformation; When the residual exhibits localized, continuous, low-frequency variations, and the consistency of the sign of the residuals at adjacent sampling points is higher than a preset value, it is attributed to board warping. When there is an isolated spike in the residual, and the standard deviation of the residual in the neighborhood of the spike is lower than a preset value, it is attributed to slag adhesion.

[0010] In an optional implementation, when the residual contains both continuous low-frequency components and isolated spikes, a warped field is fitted by low-pass filtering, and the warped field is subtracted from the residual to obtain the slag-attached residual. Isolated spikes in the slag-attached residual are marked as slag-attached positions, and a warped field distribution and a list of slag-attached positions are output.

[0011] In an optional implementation, the step of selecting the corresponding coordinate compensation strategy and focus strategy for marking based on the attribution result includes: When the attribution result is board warping, the marking area is divided into multiple grids. The target height of each grid is the board surface height fitted in that grid plus the material defocusing amount. The Z-axis of the marking head is dynamically switched with the marking position. When the attribution result is slag adhesion, after removing the slag adhesion position, the height of the remaining plate point is used as the focusing reference, and the marking path is controlled to bypass the slag adhesion position or the laser power is reduced at the slag adhesion position. When the attribution result is platform deformation, the systematic offset correction caused by platform deformation is superimposed on the coordinate compensation amount, and focusing is performed with the corrected reference height.

[0012] In an optional implementation, a real-time protection step during the marking process is also included: Continuously monitor the real-time height residual. When the real-time height residual exceeds the foreign object threshold, immediately shut down the laser, raise the Z-axis, and trigger an emergency stop. When the real-time height residual continues to increase and exceeds the warping threshold, switch to the zone focus mode or reduce the marking speed. When the real-time height residual is an occasional spike and the frequency of occurrence is lower than the preset value, logs are recorded without interrupting processing.

[0013] Secondly, the present invention provides a dual-layer exchange platform gantry marking control system, comprising: The first acquisition module is used to control the gantry to drive the single-point laser rangefinder to scan along the material-free reference area of ​​the rack structure after the platform exchange is in place, acquire the first height sequence, extract the periodic features of the first height sequence, and determine the measured tooth pitch based on the periodic features. The identity determination module is used to compare the measured tooth pitch with the pre-stored upper platform template and lower platform template respectively, and determine the identity of the currently positioned platform based on the comparison results; The second acquisition module is used to determine the reference height based on the identity of the current platform and the measured statistics of the first height sequence, to sample the second height sequence of the plate area using the single-point laser rangefinder and to calculate the residual of the second height sequence, and to attribute the residual according to the spatial distribution pattern of the residual in order to distinguish between plate warping, slag adhesion and platform deformation. The strategy determination module is used to select the corresponding coordinate compensation strategy and focus strategy to perform labeling based on the attribution results.

[0014] The beneficial effects of this invention are as follows: The double-layer exchange platform gantry marking control method and system provided by this invention utilizes the periodic height spectrum of the rack structure of the exchange platform itself as a spatial scale. This allows the single-point rangefinder to automatically complete platform identity determination and dynamic benchmark correction after the platform is in place, without the need for additional vision or point cloud sensors. This solves the problems of misjudgment when the upper and lower platforms are at similar heights and benchmark drift after heavy load. Through the causal logic of benchmark area verification and plate area residual attribution, plate warping, slag buildup, and platform deformation are distinguished, avoiding accidental emergency stops triggered by slag buildup. This ensures consistent focusing across the entire area under warping conditions, improving marking quality and production line uptime. Attached Figure Description

[0015] 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, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic flowchart of a method according to an embodiment of the present invention.

[0017] Figure 2 This is a schematic block diagram of a system according to an embodiment of the present invention. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0020] The dual-layer exchange platform gantry marking control method provided in this embodiment of the invention is executed by a computer device, and correspondingly, the dual-layer exchange platform gantry marking control system runs in the computer device.

[0021] Figure 1 This is a schematic flowchart illustrating a method according to an embodiment of the present invention. Wherein, Figure 1 The executing entity can be a two-layer exchange platform gantry marking control system. Depending on different requirements, the order of steps in this flowchart can be changed, and some steps can be omitted.

[0022] like Figure 1 As shown, the method includes: S1. After the platform is in place, control the gantry to drive the single-point laser rangefinder to scan along the material-free reference area of ​​the rack structure, collect the first height sequence, extract the periodic features of the first height sequence, and determine the measured tooth pitch based on the periodic features; S2. Compare the measured tooth pitch with the pre-stored upper platform template and lower platform template respectively, and determine the identity of the currently positioned platform based on the comparison results; S3. Based on the identity of the current platform and the measured statistics of the first height sequence, determine the reference height, use the single-point laser rangefinder to sample the second height sequence of the plate area and calculate the residual of the second height sequence, and attribute the residual according to the spatial distribution pattern of the residual to distinguish between plate warping, slag adhesion and platform deformation. S4. Based on the attribution results, select the corresponding coordinate compensation strategy and focus strategy to perform the labeling.

[0023] The hardware deployment of this invention includes: Double-layer exchange platform: The upper and lower platforms are arranged in parallel, allowing for alternating access to the laser cutting station inside the main unit and the external gantry marking station along guide rails. The support surfaces of both platforms adopt a periodic rack and pinion structure, with the racks arranged at equal intervals along the X-direction to form the platform's own reference space scale.

[0024] External gantry marking unit: Independent of the cutting host, spanning above the marking station, it includes the gantry's X / Y servo travel axes, the marking head's Z-axis lifting servo, and a laser marking device. The gantry drives the marking head in two-dimensional motion above the station to complete the marking trajectory.

[0025] Single-point laser rangefinder: Rigidly mounted on the gantry marking mechanism, linked with the gantry's X / Y axes. It provides a 0-10V analog output, with a measuring range corresponding to a height of 0–800mm. The output signal is connected to the motion controller, and the actual height H is calculated as H = U × 80 (mm / V). The installation position must ensure that the measuring spot covers the platform rack reference area and the material area, without obstructing the laser marking beam path or being directly exposed to cutting shards.

[0026] Motion controller: Acquires analog signals from the rangefinder and position signals from the gantry encoder, performs pitch spectrum verification, residual attribution, and working condition adaptation logic, and outputs control commands to the gantry servo axis, Z-axis lifting servo, and laser marking device.

[0027] The host control system is responsible for the dual-layer platform exchange logic and internal laser cutting control. After the platform is in place, it sends a start signal to the marking controller and executes subsequent exchange actions after receiving the marking completion signal.

[0028] Display screen / HMI: Used for parameter input, status monitoring and alarm display.

[0029] Based on the above hardware deployment, the steps of this invention will be described in detail.

[0030] In one embodiment of the present invention, based on step S1, the following will provide a possible embodiment and describe its specific implementation in a non-limiting manner.

[0031] After the platform is in place, the host control system sends a start signal to the marking controller. The marking controller controls the X / Y axis movement of the gantry, moving the single-point laser rangefinder to the material-free reference area above the rack structure. The material-free reference area is a rectangular area on the platform where no sheet metal is placed and the rack structure is exposed; its position is pre-calibrated and stored in the controller.

[0032] The gantry moves the rangefinder along the X-axis (rack arrangement direction) at a constant speed with a preset sampling interval, simultaneously collecting the X-axis position of each sampling point and the rangefinder's output voltage value. The controller converts the voltage value into a height value according to a preset voltage-height conversion relationship.

[0033] in The output voltage (V) of the rangefinder. The measured heights are in mm. Arranged in sampling order to form the first height sequence:

[0034] in For the first The X-axis coordinates of the gantry at each sampling point This corresponds to the measured height. This represents the total number of sampling points. The sampling interval is set to an integer fraction of the rack pitch, ensuring that each rack pitch period contains at least 5 sampling points to guarantee the resolution of subsequent periodic feature extraction.

[0035] Periodic features are extracted from the first altitude sequence. This embodiment employs autocorrelation analysis, and its autocorrelation function is defined as:

[0036] in This represents the number of lagging sampling points. The mean of the first altitude sequence:

[0037] Autocorrelation function A peak occurs at the hysteresis position corresponding to the tooth pitch. Extract the number of hysteresis points corresponding to the first significant peak. Combined with sampling interval Calculate the measured tooth pitch:

[0038] Simultaneously, peak detection is performed on the first height sequence to extract the tooth tip position sequence. and tooth valley position sequence And calculate the average tooth tip height and average tooth valley height:

[0039]

[0040] As measured tooth pitch Cross-validation can also be calculated from the average of the differences between adjacent tooth tip positions:

[0041] when and If the deviation is within the preset tolerance range, the periodic feature extraction is deemed valid; otherwise, the reference area scanning is deemed abnormal, an alarm signal is output, and a rescan is requested.

[0042] In one embodiment of the present invention, based on step S2, the following will provide a possible embodiment and describe its specific implementation in a non-limiting manner.

[0043] The controller pre-stores upper and lower platform templates. Each platform template is created during the equipment initialization phase as follows: the upper and lower platforms are swapped to the marking station under no-load conditions, their respective first height sequences are collected using the aforementioned reference area scanning method, and the corresponding tooth pitch template values ​​are extracted. , Average tooth tip height template value , template value of average height of tooth valley , And the template value of the standard deviation of the tooth tip height , Template value of standard deviation of tooth valley height , The data is stored in the controller's non-volatile memory.

[0044] After the platform is in place and the reference area scan is completed, the controller will measure the tooth pitch. The tooth pitch of the upper platform template is respectively and lower platform template tooth pitch Compare and calculate the tooth pitch deviation:

[0045]

[0046] Setting pitch tolerance (For example, take) ).like and If so, then the current platform is determined to be the previous platform; if and If so, the current platform is determined to be the next platform.

[0047] when and When the tooth pitch of the two platforms is close, further auxiliary judgment is made using the average tooth tip height and the average tooth valley height. The deviation between the measured average tooth tip height and the templates of the two platforms is calculated:

[0048]

[0049] And the deviation between the measured average tooth valley height and the templates of the two platforms:

[0050]

[0051] Construct a comprehensive matching score:

[0052]

[0053] The weights satisfy ,and This embodiment takes , , The platform corresponding to the higher scorer will be used as the current platform for arrival.

[0054] When both scores are below the preset reliability threshold (For example, take) If the platform's identity cannot be confirmed, an alarm signal will be output, indicating that the platform is not in place or the rack structure is abnormal, and the marking process will be prohibited from starting.

[0055] when and If the measured tooth pitch does not match either of the two platform templates, the amplitude of the main peak of the autocorrelation function is further checked. If the amplitude of the main peak is lower than the preset threshold, the periodic characteristics of the reference area are not obvious, which may be due to contamination of the rangefinder or foreign objects covering the platform surface, and a corresponding alarm signal is output. If the amplitude of the main peak is normal but the tooth pitch is deviated, the rack structure is abnormal or the platform is installed backwards, and an alarm signal is output and a manual inspection is requested.

[0056] In one embodiment of the present invention, based on step S3, the following will provide a possible embodiment and describe its specific implementation in a non-limiting manner.

[0057] S301. Determination of Reference Height Once the platform identity is confirmed, the controller corrects the preset platform reference height based on the measured statistics of the first height sequence to obtain the reference height for this marking.

[0058] The controller reads the average tooth tip height of the first height sequence. and average height of the dentition valley Calculate the overall measured height:

[0059] Read the template reference height corresponding to this platform (The overall average height of the tooth crest and tooth valley pre-stored in the upper or lower platform template), calculate the overall offset:

[0060] Simultaneously calculate the standard deviation of tooth tip height and tooth trough height:

[0061]

[0062] Set the first threshold (For example, take) ), second threshold (For example, take) ), third threshold (For example, take) Determine the reference height according to the following rules: when and and At that time, the platform was in normal condition, and the actual measured overall height was used as the reference height:

[0063] when and When determining whether the platform has sunk or risen, the reference height is the template base height plus the offset.

[0064] And record the platform's deformation log. When If the platform deformation exceeds the tolerance, marking is prohibited and an alarm signal is output.

[0065] when or When it is determined that there is local deformation in the rack structure, the tooth tip height or tooth trough height exceeds the limit. Tooth positions within a certain range are marked as abnormal and excluded from the set of reliable reference points:

[0066] by The overall measured height is recalculated for the points in the middle, and the reference height is determined according to the above rules. .

[0067] S302. Acquisition and Residual Calculation of the Second Height Sequence in the Plate Area After the reference height is determined, the controller controls the gantry to move the rangefinder along a preset edge-following trajectory above the board area, collecting the height values ​​of each sampling point at preset sampling intervals. Based on the reference height, lower and upper threshold values ​​for candidate points on the board are set.

[0068]

[0069] in Minimum plate thickness (e.g., take) ), For the maximum plate thickness (e.g., take...) ), For the tolerance height of slag (e.g., take the following) ). Place the height value The sampling points within the plate are marked as candidate points, forming a second height sequence:

[0070] With a set of reliable benchmarks Fitting the global reference plane:

[0071] Where the coefficient , , Solve using the least squares method. Calculate the residuals for each candidate point on the plate:

[0072] S303. Residual Attribution Controller for residual Spatial distribution pattern analysis was performed, and attribution was performed according to the following rules: Rule 1: Platform deformation attribution. Calculate the overall systematic offset of the residuals:

[0073] when (For example, take) When the overall offset of the residual in the plate area is determined to be consistent with the overall offset of the reference area, it is attributed to the plateau deformation. Subtracting this offset from the residual yields the residual after removing the plateau deformation:

[0074] Rule 2: Attribution of Sheet Warpage. This involves considering the residuals after removing the plateau deformation. Calculate its standard deviation:

[0075] in for The mean. When (For example, take) ), and the consistency of the sign of the residuals of adjacent sampling points is higher than a preset ratio (e.g. When the residual shows a localized, continuous, low-frequency change, it is attributed to the warping of the board material.

[0076] Rule 3: Slag Adhesion Attribution. This applies to the residuals after platform deformation. Detect isolated spikes. For each sampling point, calculate the radius centered on that point. Local standard deviation within the neighborhood:

[0077] in For the first Centered on a point, with a radius of... The neighborhood point set within, The number of neighboring points. Let be the mean of the neighborhood residuals. (For example, take) )and (For example, take) When the point is identified as an isolated spike, it is attributed to slag buildup, and its coordinates are recorded.

[0078] Rule 4: Handling of Complex Operating Conditions. When the residual contains both continuous low-frequency components and isolated spikes, first fit the warped field using a low-pass filter. Then, subtract the warping field from the residual to obtain the slag residue:

[0079] right Isolated spikes in the data are marked as slag-laden locations according to rule three, and the warp field distribution and a list of slag-laden locations are output.

[0080] Rule 5: Foreign Object Attribution. When the height of a sampling point satisfies:

[0081] in Determine the margin for foreign objects (e.g., take...) If the object is identified as a foreign object or residue, an emergency stop will be triggered immediately and an alarm signal will be output.

[0082] After attribution is completed, the controller outputs the working condition classification results: normal plane, plate warping, slag adhesion, platform deformation, foreign objects or composite working conditions, for subsequent coordinate compensation and focusing strategy calls.

[0083] In one embodiment of the present invention, based on step S4, the following will provide a possible embodiment and describe its specific implementation in a non-limiting manner.

[0084] The controller outputs a working condition classification based on the attribution results, and selects the corresponding coordinate compensation strategy and focusing strategy according to the working condition type to perform marking.

[0085] S401. Normal Planar Working Condition When the attribution result is a normal plane, the controller fits the profile of the board based on the candidate points of the board in the second height sequence and calculates the X-direction offset between the actual placement position of the board and the coordinates of the preset marking graphic. Y-direction offset and rotation angle For the preset marking graphic coordinates Perform translation and rotation compensation:

[0086] The focusing strategy employs fixed-height focusing. The plate thickness is estimated based on the average height of candidate points on the plate.

[0087] The material defoaming amount is obtained by referring to a table based on the material and thickness of the sheet metal. Calculate the target height of the marking head along the Z-axis:

[0088] Control the Z-axis servo to move the marking head to Once the position is confirmed, the X / Y axes of the gantry are linked, and the laser marking device completes the marking according to the compensated graphic trajectory.

[0089] S402. Sheet Warpage Conditions When the attribution result is board warping, the coordinate compensation strategy is the same as for normal planar conditions, still correcting the coordinates of the marked graphic using translation and rotation compensation. Simultaneously, the controller records the warping field distribution. This information is then transmitted to the focus control stage.

[0090] The focusing strategy employs zone focusing. The marking area is divided according to a preset grid size (e.g., ...). The target height is divided into several grids, and the height of the target is calculated independently for each grid.

[0091] in For the first The height of the reference plane at the center of each grid. This represents the warpage amount at that location. The Z-axis is dynamically switched to the target height of the corresponding grid during the marking process, depending on the marking position. When the warpage amount satisfies:

[0092] in The upper limit of warpage (e.g., take) When warping exceeds tolerance, an alarm signal is output and manual leveling or switching to a different cutting station is recommended.

[0093] S403. Slag-laden working condition When the attribution result is slag adhesion, the controller first removes the marked slag adhesion points, refits the plate profile with the remaining candidate points, and calculates the translation amount according to the formula for normal planar operation. , and rotation angle The coordinates of the marked graphic are compensated.

[0094] The focusing strategy employs clean-point focusing. The average height of candidate points on the board material after removing areas with dross or inclusions is used as the focusing benchmark.

[0095] in This represents the set of slag-coating locations. Simultaneously, the controller calculates the slag-coating ratio based on the ratio of the number of slag-coating points to the total number of candidate points on the board.

[0096] when (For example, take) When the laser is applied, the marking path is controlled to bypass the slag-laden area. Marking is skipped at the slag-laden area or the laser power is reduced; the remaining areas are marked normally. (For example, take) When the slag is concentrated, mark the area as a no-marking zone; the remaining areas can be processed normally. If the slag buildup exceeds the tolerance, an alarm signal will be output and it will be recommended to clean and re-mark.

[0097] S404. Platform Deformation Condition When the attribution result is platform deformation, the coordinate compensation includes a systematic offset correction caused by platform deformation:

[0098] in , The coordinate offset correction amount caused by platform deformation is determined by the abnormal tooth position distribution in the reference area. The focusing strategy uses the dynamically corrected reference height. Based on this, focus is performed according to the normal planar or warped working conditions.

[0099] S405. Foreign Object Condition When the cause is attributed to a foreign object, the controller immediately shuts off the laser, raises the Z-axis to a safe clearance height, triggers an emergency stop, outputs an alarm signal indicating that a foreign object or residue has been detected, and requests manual cleaning before restarting.

[0100] S406. Combined Working Conditions When the attribution result is a composite condition, it is processed in the following order of priority: foreign objects take priority over other conditions and trigger an emergency stop; platform deformation takes priority over plate warping and slag, and the reference height and coordinate compensation amount are corrected first according to the platform deformation; if the remaining residual contains both warping and slag, the warping condition is used to perform zone focusing first, and then the slag position is processed by detour or power reduction.

[0101] S407. Real-time protection during the marking process During the marking process, the rangefinder continuously collects real-time height values, and the controller calculates the real-time residuals:

[0102] in Predict the height of the model corresponding to the current marking point. Classify the response according to the following rules: when When this occurs, a Level 1 response is triggered, immediately shutting down the laser, raising the Z-axis, and bringing the system to an emergency stop.

[0103] when Furthermore, as the value continues to increase, a three-level response is triggered, switching to a zone focus mode or reducing the marking speed.

[0104] when When the spikes are occasional and occur less frequently than a preset value (e.g., 3 times per minute), a level 4 response is triggered, logging is performed without interrupting processing.

[0105] After marking is completed, the laser is turned off, the Z-axis is raised to a safe clearance height, the gantry returns to the origin, and the controller sends a marking completion signal to the host control system.

[0106] Based on the above embodiments, in one embodiment, a real-time protection mechanism during the marking process is also provided: During the marking process, the controller continuously collects the height value of the current marking point position through a rangefinder. The sampling frequency is matched with the gantry movement speed to ensure that the distance between adjacent sampling points does not exceed a preset value. The controller then uses the coordinates of the current marking point... Read the model-predicted height of the point from the already constructed height model:

[0107] in The height is fitted to the reference plane of the board. This represents the warped field component (zero if there is no warping). The real-time height residual is defined as:

[0108] The controller responds to real-time residuals in a tiered manner according to the following rules.

[0109] Level 1 Response: Foreign Object Detection. When the real-time residual satisfies:

[0110] in Foreign object threshold (e.g., take) When the system detects a foreign object or residue below the current marking point, the controller immediately outputs a laser shutdown signal, controls the Z-axis servo to rise to a safe clearance height and triggers an emergency stop. Simultaneously, it outputs an alarm signal indicating that a foreign object has been detected and requests cleanup before restarting.

[0111] Level 2 response: Slag retest. When the real-time residual satisfies:

[0112] in For the slag-coating threshold (e.g., take...) If the current point is found to have debris, the controller pauses marking at the current point and controls the rangefinder to remeasure the point. The remeasured height is recorded as [height value missing]. If the remeasured residuals satisfy:

[0113] If the fluctuation is determined to be an occasional ranging fluctuation, the marking of that point is resumed; otherwise, it is determined to be a slag buildup, the point is marked as the slag buildup location, and the marking of that point is skipped and continues.

[0114] Level 3 response: Warpage degradation. When the real-time residual continues to increase and satisfies:

[0115] in For the warpage threshold (e.g., take...) When the residuals at multiple consecutive sampling points show a monotonically increasing trend, it is determined that the board material has undergone further warping deformation during the marking process. The controller switches to zone focusing mode, re-divides the marking area according to the preset grid, and calculates the target height for each grid independently and controls the Z-axis to dynamically follow; or reduces the marking speed to allow the Z-axis sufficient response time to track height changes. When the warping exceeds the upper limit... When the time comes, an alarm signal will be output and marking will be paused, awaiting manual confirmation.

[0116] Level 4 Response: Occasional Spike Recording. When the real-time residual exhibits an isolated spike and its frequency is lower than a preset value (e.g., 3 times per minute), it is determined to be ranging noise or slight surface contamination, and processing is not interrupted. The controller records the location, amplitude, and timestamp of the spike and stores it in the operation log for subsequent maintenance reference.

[0117] During the marking process, the controller continuously monitors the real-time residual change trend. When the residual change rate of adjacent sampling points meets the following condition:

[0118] in For sampling interval, The threshold for the rate of change of residuals (e.g., taking...) When a sudden change in height is detected, it should be handled according to the first-level response. After marking is completed, the controller summarizes the abnormal records of this marking process, including the list of slag attachment locations, warping exceeding the limit area, and the number of emergency stop triggers, and outputs them to the display screen for operators to view.

[0119] This application example uses a thick plate laser cutting composite production line as an example. This production line is equipped with a double-layer exchange platform laser cutting host and an external independent gantry laser marking unit. The host machine performs laser cutting of carbon steel and stainless steel plates, while the external gantry marking unit processes the plates with numbers, QR codes, and graphic markings before and after the cutting process. The production line primarily processes Q235 carbon steel and 304 stainless steel with a thickness of 20mm to 40mm, with plate sizes ranging from 2000mm × 1000mm to 3000mm × 1500mm.

[0120] I. Equipment Hardware Deployment The upper and lower platforms of the double-layer exchange platform are arranged in parallel, and both can alternately enter the internal cutting station and the external gantry marking station of the main unit along the guide rails. Both platforms use a rack and pinion structure for their support surfaces, with the racks evenly spaced along the X-direction. The measured tooth pitch is approximately 50mm, the tooth tip height is approximately 120mm, the tooth trough height is approximately 115mm, and the height fluctuation within a single tooth pitch cycle is approximately 5mm. After the platforms are in place, due to mechanical backlash, differences in pneumatic clamping conditions, and deformation of the support structure after long-term heavy loads, the actual reference height may deviate from the factory calibration value by several millimeters.

[0121] The external gantry marking unit spans above the marking station and includes X / Y servo travel axes, a Z-axis lifting servo for the marking head, and a fiber laser marking device. A single-point laser rangefinder is rigidly mounted on the gantry marking mechanism, moving in tandem with the gantry's X / Y axes. It provides a 0–10V analog output, a range corresponding to a height of 0–800mm, and a resolution of approximately 1mm. The rangefinder's installation position ensures that the measuring spot covers both the platform rack reference area and the material area, without obstructing the laser marking path or being directly exposed to cutting shards.

[0122] The motion controller acquires analog signals from the rangefinder and position signals from the gantry shaft encoder, performs pitch spectrum verification, residual attribution, and working condition adaptation logic, and outputs control commands to the gantry servo axis, Z-axis lifting servo, and laser marking device. The main control system is responsible for the dual-layer platform exchange logic and internal laser cutting control. After the platform is in position, it sends a start signal to the marking controller, and after receiving the marking completion signal, it executes subsequent exchange actions.

[0123] II. System Initialization and Template Library Establishment After the equipment is powered on for the first time, the operator enters basic parameters through the HMI: upper platform template tooth pitch. Lower platform template tooth pitch The template parameters, including the mean height of the tooth tip, the mean height of the tooth trough, the standard deviation of the tooth tip height, and the standard deviation of the tooth trough height, are established during the equipment commissioning phase as follows: the upper and lower platforms are switched to the marking station under no-load conditions, and the gantry is controlled to drive the rangefinder to scan along the material-free reference area of ​​the rack structure at a sampling interval of 2mm. The first height sequence of each platform is collected, the tooth pitch is extracted through autocorrelation analysis, and the mean and standard deviation of the tooth tip and tooth trough heights are statistically analyzed and stored in the controller's non-volatile memory.

[0124] Simultaneously input the operating condition judgment parameter: tooth pitch tolerance. Confidence threshold First threshold Second threshold The third threshold Warp threshold slag threshold Foreign body threshold Tolerance for slag , The zoned focus grid size is 100mm.

[0125] The material defocusing amount lookup table is calibrated as follows: Test pieces of Q235 carbon steel, 304 stainless steel, aluminum plate, and galvanized plate are taken respectively, and the defocusing amount is measured under their respective optimal marking grayscale conditions, and stored in the controller. In this example, Q235 carbon steel (3–20mm) is taken as -2.0mm, Q235 carbon steel (20–50mm) as -1.5mm, 304 stainless steel (3–20mm) as +1.0mm, aluminum plate as -3.0mm, and galvanized plate as 0.0mm.

[0126] Example 1: Marking on a conventional carbon steel plate The material being processed is Q235 carbon steel, 10mm thick, 2000mm×1000mm in size. The plate is laid flat on the upper platform, with no obvious warping or slag.

[0127] After the main unit completes the cutting, the double-layer exchange mechanism activates, conveying the upper platform to the external gantry marking station. Upon arrival, the positioning sensor triggers, and the main unit sends a start signal to the marking controller. The controller then controls the gantry to move the rangefinder to the material-free reference area of ​​the rack and pinion structure, scanning along the X-direction at 2mm sampling intervals to acquire the first height sequence. Autocorrelation analysis is used to extract the measured tooth pitch. Deviation between the tooth pitch and the upper platform template Less than the tolerance ; Deviation between tooth pitch and lower platform template The value is greater than the tolerance. The currently accessed platform is determined to be the upstream platform.

[0128] Further calculate the offset between the measured overall height and the reference height of the upper platform template. Standard deviation of tooth tip height Standard deviation of tooth valley height All are less than the first threshold. ,and The platform was determined to be in normal condition, and the actual measured overall height was used as the reference height. .

[0129] The controller directs the gantry to move the rangefinder along a preset edge-following trajectory above the board area, collecting the second height sequence at 30mm sampling intervals. Based on, lower threshold Upper limit threshold Sampling points whose height values ​​fall within a threshold range are marked as candidate points for the board material. A global reference plane is fitted using a set of reliable benchmark points, and residuals are calculated for each candidate point. The standard deviation of the residuals is then calculated. maximum value It was determined to be a normal flat panel.

[0130] The controller fits the profile of the plate based on candidate points and calculates the offset in the X direction. Y-direction offset Rotation angle Perform translation and rotation compensation on the preset marking graphic coordinates. Estimate the plate thickness based on the average height of candidate points on the plate. From the table, the decoking amount of Q235 carbon steel (3–20mm) is... Calculate the target height along the Z-axis. Once the Z-axis is moved to the target height and confirmed to be in place, the X / Y axes of the gantry are linked, and the laser marking device completes the marking according to the compensated graphic trajectory.

[0131] During the marking process, the real-time residual is always present. Within the specified timeframe, no protection response was triggered. After marking was completed, the laser was shut off, the Z-axis was raised to a safe clearance height, the gantry returned to its origin, and the controller sent a marking completion signal to the host computer. The host computer then controlled the dual-layer exchange platform to return the workpiece to the internal cutting or unloading station. The entire process was smooth, the marking was clear, and the QR code recognition rate was 100%.

[0132] Example 2: Marking warped thick plates The material being processed is Q235 carbon steel, 30mm thick, with dimensions of 3000mm × 1500mm, and exhibits noticeable warping after cutting. The sheet metal is still supported by the upper platform as it enters the marking station.

[0133] The platform identity determination and reference height determination process is the same as in Example 1. Through tooth pitch spectrum comparison, the currently positioned platform is determined to be the upper platform, the platform status is normal, and the reference height is [not specified]. Take the actual measured overall height.

[0134] After acquiring the second altitude sequence via edge scanning, the controller calculates the residuals. The standard deviation of the residuals is then calculated. Exceeding the warp threshold The residual sign consistency between adjacent sampling points was 85%, higher than the preset 80%, indicating that the residuals exhibited localized continuous low-frequency variations, attributed to board warping. The controller fitted the warping field using a low-pass filter. Maximum warpage Less than the upper limit of warpage It was determined to be a mild warping.

[0135] The coordinate compensation strategy is the same as in normal planar conditions, correcting the coordinates of the marking graphic through translation and rotation compensation. The focusing strategy is switched to zone focusing. The marking area is divided into multiple grids of 100mm each, and the target height is calculated independently for each grid.

[0136] in The height of the reference plane at the center of the grid. This refers to the amount of warpage at that location. Take Q235 carbon steel (20–50mm) The Z-axis is dynamically switched to the target height of the corresponding grid during the marking process, depending on the marking position.

[0137] During the marking process, real-time residual monitoring showed that the focal length deviation within each grid was controlled within... Within this range, no Level 3 degradation response was triggered. After marking was completed, the marking clarity was consistent across the entire area, and the QR code recognition rate was 100%.

[0138] Example 3: Marking Stainless Steel Slag The material being processed is 304 stainless steel, 8mm thick, with dimensions of 1500mm × 800mm. Molten slag adheres to the cut surface. The sheet metal is carried to the marking station by a lower platform.

[0139] The controller controls the rangefinder to scan the materialless reference area of ​​the rack structure and extract the measured tooth pitch. Deviation between the tooth pitch and the lower platform template Less than the tolerance; deviation from the tooth pitch of the upper platform template. The value is greater than the tolerance. The currently accessed platform is determined to be the next platform.

[0140] During the reference height determination process, the offset between the measured overall height and the reference height of the lower platform template is... Standard deviation of tooth tip height Standard deviation of tooth valley height All are less than the first threshold, and The platform is determined to be in normal condition, and the actual measured overall height is used as the reference height.

[0141] After the edge-following scan, the controller calculates the residuals. The residuals contain multiple isolated spikes, with the largest spike being... Exceeding the slag threshold Local standard deviations within the neighborhood of these peaks Less than the local standard deviation threshold This was determined to be slag adhesion. The percentage of slag adhesion points... less than The condition was determined to be a qualified slag-hanging condition.

[0142] After the controller removes the slag-laden points, it refits the board contour using the remaining candidate points and calculates the translation amount. , Rotation angle The coordinates of the marking graphic are compensated. The focusing strategy employs clean point focusing, using the average height of candidate points on the board after removing slag-laden points as the focusing reference, and calculating the target height along the Z-axis:

[0143] in Take 304 stainless steel At the same time, the controller controls the marking path to bypass the slag-laden position, skipping the marking or reducing the laser power at the slag-laden position.

[0144] During the marking process, real-time residual monitoring showed that the non-slag-attached area was highly stable and no emergency stop was triggered. After marking was completed, an inspection showed that the marking in the non-slag-attached area was normal, the slag-attached area was skipped, there were no emergency stop records, and the production line utilization rate was not affected.

[0145] Example 4: Mixed Working Condition of Platform Deformation and Sheet Warping The material being processed is Q235 carbon steel, 20mm thick, with dimensions of 2500mm × 1200mm. Slight warping occurs after cutting. The sheet metal is carried to the marking station by an upper platform. This upper platform has been operating continuously for several months, and the supporting structure has experienced localized subsidence.

[0146] After the controller scans the material-free reference area of ​​the rack structure, it extracts the measured tooth pitch. Deviation between the tooth pitch and the upper platform template The platform currently in use is determined to be the platform above.

[0147] The offset between the measured overall height and the template reference height during the reference height determination process. greater than the second threshold Less than the third threshold The overall platform is determined to be sinking. Standard deviation of tooth tip height. greater than the first threshold The controller determined that the rack structure had localized deformation. The controller then adjusted the rack height to exceed... Tooth positions within the specified range are marked as abnormal and excluded from the set of reliable reference points. The reference height is then recalculated using the remaining reliable reference points.

[0148] After the edge-following scan, the controller calculates the residuals. The overall systematic offset of the residuals. Overall offset from the reference area The deviation is Less than the matching threshold The overall offset of the residual in the plate area is determined to be consistent with the overall offset in the reference area, which is attributed to the plateau deformation. Subtracting this offset from the residual yields the residual after removing the plateau deformation. .right Further analysis revealed the residual standard deviation. Exceeding the warp threshold The sign consistency of the residuals between adjacent sampling points was 82%, and the remaining residuals were determined to be attributed to board warping.

[0149] The coordinate compensation includes a systematic offset correction caused by platform deformation. The focusing strategy uses the dynamically corrected reference height. Based on this, zone focusing is performed according to the warped condition. During the marking process, real-time residual monitoring shows that the focal length deviation within each grid is controlled within... Within [the specified range]. After marking was completed and inspected, the markings were clear throughout the entire area, successfully separating the effects of platform deformation and sheet warping.

[0150] Example 5: Foreign Object Detection The material being processed is Q235 carbon steel, 16mm thick, with dimensions of 2000mm × 1000mm. After the previous plate was cut, a piece of residual material was not completely removed and remained in the gap between the platform racks.

[0151] The platform identity verification and reference height determination process proceeded normally. The currently positioned platform was determined to be the upper platform, and the platform status is normal. After the edge scan collects the second height sequence, the controller calculates the residual. Height of a certain sampling point. Exceeding the foreign object detection threshold If the object is identified as a foreign object or residue, the controller immediately triggers a Level 1 response, shutting down the laser, raising the Z-axis and stopping it abruptly, outputting an alarm signal to indicate that a foreign object has been detected and requesting cleaning before restarting.

[0152] After the operator cleans up the residual material, the marking process is restarted. The controller re-executes platform identity determination, reference height determination, edge scanning, and residual attribution. After confirming that there are no abnormalities, the marking is completed under normal planar conditions.

[0153] Example 6: Combined Working Condition of Warpage and Slag Adhesion The material being processed is 304 stainless steel, 15mm thick, with dimensions of 2000mm × 1000mm. After cutting, it exhibits both warping and localized slag buildup. The sheet metal is carried to the marking station by a lower platform.

[0154] The platform identity was determined to be the downstream platform, and the platform status is normal. After the edge scan, the controller calculates the residuals. The residuals contain both continuous low-frequency components and isolated spikes: residual standard deviation. Exceeding the warp threshold Multiple isolated spikes exist simultaneously, with the largest spike value being... Exceeding the slag threshold And the local standard deviation of the peak neighborhood less than The condition was determined to be a combination of warping and slag adhesion.

[0155] The controller processes the composite operating conditions by first fitting the warped field through a low-pass filter. Then, subtract the warping field from the residual to obtain the slag residue:

[0156] right Isolated spikes are marked as dross locations. Output warp field distribution and a list of dross locations. The coordinate compensation strategy incorporates the effects of warp and dross removal. The focusing strategy performs zoned focusing under warp conditions, and bypasses dross areas according to the acceptable dross conditions. After marking, an inspection is performed; both conditions are correctly handled simultaneously, marking is clear in non-dross areas, and dross areas are skipped, with no emergency stops recorded.

[0157] This application example validates the effectiveness of the method under six typical operating conditions. Tooth pitch spectrum verification ensures platform identification is unaffected by the similarity in height between upper and lower platforms; measured statistics in the reference area allow for dynamic correction of the reference height as the platform deforms; residual spatial distribution pattern attribution distinguishes warping, slag buildup, and platform deformation; and the operating condition adaptation strategy enables stable operation of the equipment under complex conditions without manual intervention. The entire process utilizes only a single-point laser rangefinder and the existing motion axis of the gantry, without introducing vision or point cloud sensors. It does not obstruct the cutting light path, is unaffected by cutting spatter, and adapts to the cycle time and cost constraints of thick plate cutting production lines.

[0158] In some embodiments, the dual-layer exchange platform gantry marking control system may include multiple functional modules composed of computer program segments. The computer programs of each program segment in the dual-layer exchange platform gantry marking control system may be stored in the memory of a computer device and executed by at least one processor to perform (see details). Figure 1 (Description) Functions of the gantry marking control on the dual-layer exchange platform.

[0159] In this embodiment, the dual-layer exchange platform gantry marking control system can be divided into multiple functional modules according to its functions, such as... Figure 2 As shown. The module referred to in this invention is a series of computer program segments that can be executed by at least one processor and perform a fixed function, and is stored in memory. In this embodiment, the functions of each module will be described in detail in subsequent embodiments.

[0160] The first acquisition module is used to control the gantry to drive the single-point laser rangefinder to scan along the material-free reference area of ​​the rack structure after the platform exchange is in place, acquire the first height sequence, extract the periodic features of the first height sequence, and determine the measured tooth pitch based on the periodic features. The identity determination module is used to compare the measured tooth pitch with the pre-stored upper platform template and lower platform template respectively, and determine the identity of the currently positioned platform based on the comparison results; The second acquisition module is used to determine the reference height based on the identity of the current platform and the measured statistics of the first height sequence, to sample the second height sequence of the plate area using the single-point laser rangefinder and to calculate the residual of the second height sequence, and to attribute the residual according to the spatial distribution pattern of the residual in order to distinguish between plate warping, slag adhesion and platform deformation. The strategy determination module is used to select the corresponding coordinate compensation strategy and focus strategy to perform labeling based on the attribution results.

[0161] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A method for controlling gantry marking on a double-layer exchange platform, wherein the double-layer exchange platform includes an upper platform and a lower platform that can alternately enter the gantry marking station, the support surfaces of the upper platform and the lower platform both have a periodic rack and pinion structure, and a single-point laser rangefinder is provided on the gantry marking station, characterized in that, include: After the platform is in place, the gantry is controlled to drive the single-point laser rangefinder to scan along the material-free reference area of ​​the rack structure, collect the first height sequence, extract the periodic features of the first height sequence, and determine the measured tooth pitch based on the periodic features. The measured tooth pitch is compared with the pre-stored upper platform template and lower platform template respectively, and the identity of the currently positioned platform is determined based on the comparison results; Based on the identity of the current platform and the measured statistics of the first height sequence, a reference height is determined. The second height sequence is sampled in the plate area using the single-point laser rangefinder, and the residual of the second height sequence is calculated. The residual is attributed according to the spatial distribution pattern of the residual to distinguish between plate warping, slag adhesion, and platform deformation. Based on the attribution results, select the corresponding coordinate compensation strategy and focus strategy to perform the labeling.

2. The method according to claim 1, characterized in that, The step of extracting the periodic features of the first height sequence and determining the measured tooth pitch based on the periodic features includes: Perform autocorrelation analysis or peak detection on the first height sequence to extract the tooth tip position sequence and tooth valley position sequence; The average difference between adjacent tooth tip positions is used as the measured tooth pitch, and the average tooth tip height and average tooth valley height are statistically analyzed.

3. The method according to claim 2, characterized in that, The step of comparing the measured tooth pitch with the pre-stored upper platform template and lower platform template, and determining the identity of the currently positioned platform based on the comparison results, includes: When the deviation between the measured tooth pitch and the tooth pitch of a certain platform template is within the tolerance range, and the average tooth tip height and the average tooth valley height both fall within the corresponding range of the platform template, the currently positioned platform is determined to be the platform corresponding to the template. When the deviation between the measured tooth pitch and the tooth pitch of the two platform templates exceeds the tolerance range, or when the correlation of the periodic feature is lower than the preset threshold, it is determined that the platform is not in place or the rack structure is abnormal, and an alarm signal is output.

4. The method according to claim 2, characterized in that, The determination of the reference altitude based on the identity of the currently arriving platform and the measured statistics of the first altitude sequence includes: Calculate the standard deviation of the tooth tip height sequence, the standard deviation of the tooth valley height sequence, and the overall offset of the comprehensive height value calculated from the mean tooth tip height and the mean tooth valley height relative to the corresponding platform template; When both the standard deviation of the tooth tip height and the standard deviation of the tooth valley height are less than the first threshold, and the overall offset is less than the second threshold, the overall value is used as the reference height. When the overall offset is greater than or equal to the second threshold and less than the third threshold, the reference height is the platform template plus the overall offset, and the platform deformation position is recorded. When the overall offset is greater than or equal to the third threshold, the platform deformation is determined to be out of tolerance, marking is prohibited and an alarm signal is output.

5. The method according to claim 1, characterized in that, The step of sampling the second height sequence of the plate area using the single-point laser rangefinder includes: Based on the reference height, the lower threshold of the candidate points of the board is set as the sum of the reference height and the minimum board thickness, and the upper threshold is the sum of the reference height, the maximum board thickness and the slag tolerance. The gantry is controlled to drive the single-point laser rangefinder to travel along a preset edge-following trajectory above the board area. The height value of each sampling point is collected at a preset sampling interval. Sampling points whose height values ​​fall between the lower threshold and the upper threshold are marked as candidate points of the board, forming the second height sequence.

6. The method according to claim 1, characterized in that, The attribution of residuals based on their spatial distribution patterns to differentiate between plate warping, slag adhesion, and plateau deformation includes: Calculate the overall systematic offset of the residual, compare the overall systematic offset with the overall offset of the first height sequence, and if the two are consistent, it is attributed to platform deformation; When the residual exhibits localized, continuous, low-frequency variations, and the consistency of the sign of the residuals at adjacent sampling points is higher than a preset value, it is attributed to board warping. When there is an isolated spike in the residual, and the standard deviation of the residual in the neighborhood of the spike is lower than a preset value, it is attributed to slag adhesion.

7. The method according to claim 6, characterized in that, When the residual contains both continuous low-frequency components and isolated spikes, the warped field is fitted by low-pass filtering, and the warped field is subtracted from the residual to obtain the slag-attached residual. The isolated spikes in the slag-attached residual are marked as slag-attached positions, and the warped field distribution and slag-attached position list are output.

8. The method according to claim 1, characterized in that, The step of selecting the corresponding coordinate compensation strategy and focus strategy for labeling based on the attribution results includes: When the attribution result is board warping, the marking area is divided into multiple grids. The target height of each grid is the board surface height fitted in that grid plus the material defocusing amount. The Z-axis of the marking head is dynamically switched with the marking position. When the attribution result is slag adhesion, after removing the slag adhesion position, the height of the remaining plate point is used as the focusing reference, and the marking path is controlled to bypass the slag adhesion position or the laser power is reduced at the slag adhesion position. When the attribution result is platform deformation, the systematic offset correction caused by platform deformation is superimposed on the coordinate compensation amount, and focusing is performed with the corrected reference height.

9. The method according to claim 1, characterized in that, It also includes real-time protection steps during the marking process: Continuously monitor the real-time height residual. When the real-time height residual exceeds the foreign object threshold, immediately shut down the laser, raise the Z-axis, and trigger an emergency stop. When the real-time height residual continues to increase and exceeds the warping threshold, switch to the zone focus mode or reduce the marking speed. When the real-time height residual is an occasional spike and the frequency of occurrence is lower than the preset value, logs are recorded without interrupting processing.

10. A dual-layer exchange platform gantry marking control system, used to implement the method as described in any one of claims 1-9, characterized in that, include: The first acquisition module is used to control the gantry to drive the single-point laser rangefinder to scan along the material-free reference area of ​​the rack structure after the platform exchange is in place, acquire the first height sequence, extract the periodic features of the first height sequence, and determine the measured tooth pitch based on the periodic features. The identity determination module is used to compare the measured tooth pitch with the pre-stored upper platform template and lower platform template respectively, and determine the identity of the currently positioned platform based on the comparison results; The second acquisition module is used to determine the reference height based on the identity of the current platform and the measured statistics of the first height sequence, to sample the second height sequence of the plate area using the single-point laser rangefinder and to calculate the residual of the second height sequence, and to attribute the residual according to the spatial distribution pattern of the residual in order to distinguish between plate warping, slag adhesion and platform deformation. The strategy determination module is used to select the corresponding coordinate compensation strategy and focus strategy to perform labeling based on the attribution results.

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