Concrete 3D printing path planning method, system, device and medium

Abstract

The application relates to the technical field of 3D printing, and specifically provides a concrete 3D printing path planning method, system, device and medium, which comprises the following steps: analyzing a three-dimensional model through structural mechanics, identifying a key load-bearing area, and generating a printing sequence which can preferentially guarantee the structural integrity of the key load-bearing area; adaptively and dynamically layering each block, and planning a transition area for a layer-thickness-changing area; generating a printing path trajectory of each layer and the transition area, and binding a printing speed and an extrusion rate determined based on a material deposition model to a trajectory point while the trajectory is generated; in the printing process, real-time scanning of a surface topography of a printed layer is performed, deviation data is generated by comparing the surface topography with a theoretical contour, and a reference plane height and an extrusion rate of a subsequent printing layer are dynamically corrected according to the deviation data. The application significantly improves the component size precision, compactness and construction quality, and provides a core technical guarantee for reliable printing of high-performance concrete structures.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology, specifically relating to a method, system, equipment, and medium for 3D printing path planning in concrete. Background Technology

[0002] Traditional path planning methods for concrete 3D printing primarily rely on geometric slicing of the 3D model, with the core objective of filling the model space with material. This method generally suffers from several inherent drawbacks: First, path planning is disconnected from the structural mechanical properties of the component; the printing path fails to prioritize the continuity and integrity of critical load-bearing areas, posing a risk of structural weakness. Second, the layer thickness is usually fixed, making it difficult to balance printing efficiency with the forming accuracy of complex geometric features. Third, the printing process is mostly open-loop controlled, unable to detect and compensate for accumulated errors and deformations during material deposition in real time, resulting in poor dimensional accuracy and uneven internal density in the formed components. These problems severely restrict the reliable application of concrete 3D printing technology in high-performance applications such as load-bearing structures. Therefore, there is an urgent need for an intelligent path planning method that deeply integrates structural performance, material properties, and process control. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the prior art, the present invention provides a concrete 3D printing path planning method, system, equipment and medium to solve the above-mentioned technical problems.

[0004] In a first aspect, the present invention provides a method for path planning in concrete 3D printing, comprising:

[0005] Structural mechanics analysis is performed based on the three-dimensional digital model of the component to be printed to identify key load-bearing areas, and a printing sequence is generated to prioritize the structural integrity of the key load-bearing areas. Each block in the printing sequence is adaptively and dynamically layered sequentially, and transition areas are planned for regions where the layer thickness changes. Generate printing path trajectories for each layer and transition zone, and while generating the trajectory, bind the printing speed and extrusion rate determined based on the material deposition model to each point of the trajectory; During the printing process, the surface morphology of the printed layer is scanned in real time and compared with the corresponding theoretical contour to generate deviation data; and the reference plane height and extrusion rate at the path point of the subsequent printed layer are dynamically corrected based on the deviation data.

[0006] Secondly, the present invention provides a concrete 3D printing path planning system, comprising: The sequence generation module is used to perform structural mechanics analysis based on the three-dimensional digital model of the component to be printed, identify key load-bearing areas, and generate a printing sequence that prioritizes the structural integrity of the key load-bearing areas. The block layering module is used to adaptively and dynamically layer each block in the printing sequence and plan transition areas for areas where the layer thickness changes. The parameter binding module is used to generate the printing path trajectory of each layer and the transition zone, and while generating the trajectory, binds the printing speed and extrusion rate determined based on the material deposition model to each point of the trajectory; The parameter correction module is used to scan the surface morphology of the printed layer in real time during the printing process and compare it with the corresponding theoretical contour to generate deviation data; and dynamically correct the reference plane height and extrusion rate at the path point of the subsequent printed layer based on the deviation data.

[0007] Thirdly, a device is provided, comprising: Memory for storing concrete 3D printing path planning programs; A processor is configured to implement the steps of the concrete 3D printing path planning method as provided in the first aspect when executing the concrete 3D printing path planning program.

[0008] Fourthly, a computer-readable medium is provided, on which a concrete 3D printing path planning program is stored, wherein when the concrete 3D printing path planning program is executed by a processor, the concrete 3D printing path planning method as provided in the first aspect is implemented.

[0009] The beneficial effects of this invention are as follows: the concrete 3D printing path planning method, system, equipment, and medium provided by this invention drive the printing sequence planning through structural mechanics analysis, fundamentally ensuring the load-bearing capacity and structural safety of the final component. Adaptive dynamic layering and transition zone design significantly improves overall printing efficiency while ensuring the forming accuracy of complex geometric features. Strong coupling and binding of process parameters and motion trajectory suppresses printing defects at the source. In particular, through real-time three-dimensional perception and closed-loop control, errors can be dynamically compensated, greatly improving the dimensional accuracy, internal density, and overall construction quality of the formed component, providing core technical support for the reliable printing of high-performance concrete structures. Attached Figure Description

[0010] 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.

[0011] Figure 1 This is a schematic flowchart of a method according to an embodiment of the present invention.

[0012] Figure 2This is a schematic block diagram of a system according to an embodiment of the present invention.

[0013] Figure 3 This is a schematic diagram of the structure of a device provided in an embodiment of the present invention. Detailed Implementation

[0014] 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.

[0015] 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.

[0016] The following explains the custom terms that appear in this invention: Material deposition models are the core theoretical basis for path planning in concrete 3D printing. They establish the mathematical relationship between the motion parameters of the printing equipment and the geometric characteristics of material deposition. Essentially, this model is a physical equation that quantitatively describes the material extrusion behavior. By parameterizing the printing process, it provides a theoretical foundation for achieving precise path-process coordinated control.

[0017] The core formula of the material deposition model is the volume conservation equation, the most common expression of which is as follows: .

[0018] E is the extrusion rate, referring to the volume of material extruded from the extruder per unit time, measured in cubic millimeters per second. V is the printing speed, the speed at which the print head moves while depositing material, measured in millimeters per second. W is the trajectory width, referring to the width of a single trajectory formed by the extruded material on the substrate, measured in millimeters. H is the layer height, referring to the thickness of a single layer of printed material, measured in millimeters. K is the material coefficient, a dimensionless correction factor used to compensate for deviations between the ideal model and actual printing; it comprehensively reflects the influence of factors such as material rheology, extruder efficiency, and extruder shape.

[0019] The principle of this model is based on a core physical law: conservation of mass / volume. That is, under steady printing conditions, the volume of material extruded from the extruder per unit time must be equal to the volume of material deposited on the printing platform per unit time.

[0020] Material volume at the extrusion end: During time Δt, the print head moves a distance of V×Δt. The material deposited over this distance forms a rectangular trajectory (for simplicity), with a volume of... .

[0021] Conservation principle: Therefore, the volume deposited per unit time, i.e., the extrusion rate E, is:

[0022] Introducing a correction coefficient k: The above describes the ideal situation. In reality, after extrusion, the material exhibits necking or spreading, the cross-section is not a standard rectangle, and there are effects such as extrusion delay and slippage. Therefore, an empirical coefficient k is needed for correction to ensure that the model predictions match the measured values. k is usually obtained through experimental calibration.

[0023] The engineering significance of the model: Process parameter coupling: This formula tightly couples four key process parameters (E, V, W, H). In path planning, once three of these parameters are determined, the fourth parameter must be adjusted accordingly based on this formula; otherwise, printing defects will occur.

[0024] Defect control: If E remains constant while V increases, it will lead to a decrease in W and / or H, resulting in material stringing or an excessively thin cross-section. If V decreases while E remains constant, it will lead to material accumulation and excessive thickness. The foundation of intelligent control: It is the theoretical cornerstone for achieving strong coupling between path and process parameters. For example, when printing corners, the system will predict from the model and simultaneously reduce E while decelerating to avoid material accumulation.

[0025] In practical applications, this model is dynamic and scalable.

[0026] Parameter calibration: A calibration experiment is required before actual printing. By fixing two of V, W, and H, and varying the third, a qualified E is measured. The optimal k value is then determined through inversion calculation or curve fitting.

[0027] Application in the transition zone: In the transition zone generated by dynamic stratification, the layer height H varies. To maintain the stability of the deposition cross-sectional area A = W × H (thus maintaining density), the model guides the system to dynamically adjust the trajectory width W: W = A / H. In this case, if the velocity V remains constant, the extrusion rate E can also remain constant, simplifying the control logic.

[0028] The concrete 3D printing path planning method provided in this embodiment of the invention is executed by a computer device, and correspondingly, the concrete 3D printing path planning system runs in the computer device.

[0029] 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 concrete 3D printing path planning system. Depending on different requirements, the order of steps in this flowchart can be changed, and some can be omitted.

[0030] like Figure 1 As shown, the method includes: S1. Perform structural mechanics analysis based on the three-dimensional digital model of the component to be printed, identify key load-bearing areas, and generate a printing sequence that prioritizes the structural integrity of the key load-bearing areas. S2. Perform adaptive dynamic layering on each block in the printing sequence, and plan transition areas for regions where the layer thickness changes; S3. Generate the printing path trajectory for each layer and transition zone, and while generating the trajectory, bind the printing speed and extrusion rate determined based on the material deposition model to each point of the trajectory; S4. During the printing process, the surface morphology of the printed layer is scanned in real time and compared with the corresponding theoretical contour to generate deviation data; and the reference plane height and extrusion rate at the path point of the subsequent printed layer are dynamically corrected based on the deviation data.

[0031] 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.

[0032] S101. Perform finite element analysis on the three-dimensional digital model of the component to be printed, and obtain the stress distribution inside the model by solving the problem.

[0033] A load-bearing wall with door and window openings was selected as the component to be printed. First, its BIM model was imported into finite element analysis software (such as Abaqus or ANSYS) for structural mechanics analysis. According to building codes, gravity loads were applied to simulate self-weight, and the bottom of the wall was set as a fixed constraint. After mesh generation, the solution was calculated, and the first principal stress and Mises equivalent stress distribution contour maps of the model were extracted.

[0034] S102. Based on the stress distribution, identify key load-bearing areas where the stress exceeds a preset threshold.

[0035] Set a stress threshold (e.g., 1.5 times the average stress value), and automatically filter and mark all areas with stress higher than the threshold in the stress cloud map. Identify these areas as critical load-bearing areas, such as the edges of walls and the area around openings.

[0036] S103. Based on the distribution of the critical load-bearing areas, the entire printed component is divided into multiple sub-blocks, and each sub-block is assigned a printing priority based on its stress level and structural importance.

[0037] Based on the stress cloud map, the K-means clustering algorithm is used to partition the model. Specifically, the coordinates and stress value of each pixel are used as feature vectors for clustering, thereby automatically dividing continuous areas with similar stress levels into the same sub-block. Ultimately, multiple sub-blocks are formed, including high-stress core areas (such as the lintel area above the opening), medium-stress transition areas (such as the middle of the wall), and low-stress non-critical areas (such as the wall portion far from the opening). Specific partitioning methods include: First, the stress contour map is meshed, assuming there are N pixels (or mesh cells) in the map. Each point i contains its spatial location information and stress value. We construct a feature vector xi to represent each point:

[0038] in, , These are the two-dimensional coordinates of pixel i; It is the stress value at that point (e.g., the first principal stress or Mises stress from the finite element analysis). It is a weighting factor used to balance the difference between coordinate dimensions and stress dimensions, and to adjust the relative importance of stress values ​​in clustering. If stress values ​​are the primary basis for clustering, A larger value should be chosen.

[0039] The mathematical goal of the K-means clustering algorithm is to cluster N data points... Divide into K sets (clustering) In this scenario, the K value is usually preset to 3, representing the high, medium, and low stress zones respectively.

[0040] The core of the K-means algorithm is to solve an optimization problem, the goal of which is to minimize the sum of squared distances from each data point to its cluster center:

[0041] It is clustering The mean of all points, i.e., the cluster center, is calculated using the following formula: . It is the distance from the feature vector x to the cluster center. Euclidean distance.

[0042] The above optimization problem is usually solved using an iterative algorithm, with the following steps: 1. Initialization: Randomly select K data points as initial cluster centers. .

[0043] 2. Allocation steps: For each data point x i It is assigned to the set of the nearest cluster center.

[0044]

[0045] This assignment criterion ensures that each point belongs to the category that is most similar to it (closest to it).

[0046] 3. Update steps: Recalculate the center of each cluster based on the newly assigned point set.

[0047]

[0048] 4. Iteration: Repeat steps 2 and 3 until the cluster centers no longer change significantly (i.e., the algorithm converges) or the maximum number of iterations is reached.

[0049] After the algorithm converges, all are assigned to the same cluster C. k A sub-block is formed by spatially continuous (connected) pixels. The final result is: Chigh: High-stress core region (cluster center μ) high The stress component value is the largest.

[0050] Cmedium: Medium stress transition zone.

[0051] Clow: Low-stress non-critical area (cluster center μ) low The stress component value is the smallest.

[0052] Subsequently, a comprehensive priority score is calculated for each sub-block. The calculation formula is: Priority Score = W1 × Average Stress Value + W2 × Stress Gradient + W3 × Regional Relative Height Coefficient + W4 × Geometric Complexity Coefficient.

[0053] The weighting coefficients [W1,W2,W3,W4] are preset to [0.5,0.2,0.2,0.1] based on expert experience, indicating a greater emphasis on load-bearing importance.

[0054] The relative height coefficient of a region is calculated as: 1 - (height of the lowest point of the sub-block / total height of the component). Therefore, the lower the sub-block is, the closer this coefficient is to 1, and its priority is significantly increased to ensure that the structure is stably built from the bottom.

[0055] The geometric complexity coefficient is determined by normalization based on the ratio of the number of sides to the area of ​​the sub-block outline, and is used to quantify the printing difficulty.

[0056] Sub-block gradient characterization: To obtain a single index representing the stress gradient level of the entire sub-block, the average or 90th percentile of the stress gradient magnitudes of all nodes within the sub-block is calculated as the stress gradient value of that sub-block.

[0057] This represents the stress gradient magnitude of the i-th node within the sub-block.

[0058] S104. The system sorts all sub-blocks in descending order of their overall priority score. Based on this, and combined with simple geometric dependency rules (e.g., lower blocks must be printed before blocks above them), a globally optimal printing sequence is generated. This sequence instructs the printer to first print the core load-bearing areas at the bottom of the wall and around openings, and then proceed upwards and towards non-critical areas, ensuring the structural integrity of the components from the outset.

[0059] 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.

[0060] S201. For each target block in the printing sequence, identify the geometric features of the target block, the geometric features including at least overhanging regions, high curvature regions and flat regions.

[0061] For any target region in the sequence (such as a high-stress core area), the 3D model of the target region is read, and geometric feature analysis is performed using computer graphics algorithms. First, the normal vector and Gaussian curvature of each point on the model surface are calculated. Classification rules are set: regions where the angle between the surface normal and the vertical direction is greater than the material's self-standing angle (e.g., 60 degrees) are marked as cantilevered regions; regions where the absolute value of the Gaussian curvature is greater than a preset curvature threshold (e.g., 0.1 mm⁻²) are marked as high-curvature regions (e.g., rounded corners, domes); and large regions where the normal is nearly vertical and the curvature is close to zero are marked as flat regions.

[0062] S202. Based on the identified geometric features, generate a layer height constraint map for the target block, wherein the layer height constraint map marks the maximum allowable layer height for different areas of the block based on geometric precision.

[0063] Based on the geometric feature recognition results, a floor height constraint map mapped to the surface of the target block is generated. The rules are as follows: In cantilevered areas, to prevent collapse, the maximum allowable floor height is set to a smaller value (e.g., 8mm); in high curvature areas, to reduce the step effect and ensure contour accuracy, the maximum allowable floor height is set to an even smaller value (e.g., 5mm); in flat areas, to improve efficiency, a larger floor height (e.g., 25mm) is allowed.

[0064] S203. Using the layer height constraint map as the main constraint, and combined with the interlayer bonding strength constraint of the material, the target block is sliced ​​from bottom to top, and a maximum layer height is dynamically determined for each layer under all constraint conditions.

[0065] Starting from the bottom of the target block, slicing is performed using the layer height constraint map as the primary constraint. For the current slice plane, the algorithm probes upwards to find a maximum allowable layer height that satisfies the layer height constraint of the current area while ensuring interlayer bond strength through material model verification. For example, starting from the bottom, a layer height of 25mm is used for flat areas; when scanning is about to enter a rounded corner (high curvature area), the layer height is automatically reduced to 5mm for fine printing.

[0066] S204. When the height difference between two adjacent floors exceeds a preset threshold, a gradual transition zone with varying floor heights is generated between them. Specifically, this includes: 1. Based on the layer height difference ΔH and the surface geometric features of the target block in the layer height variation area, dynamically calculate the length of the transition zone and the number of transition layers it contains.

[0067] Define parameter: ΔH, the absolute value of the change in floor height, i.e., ΔH = |H high -H low |。 θ surface θ is the angle (i.e., surface slope) between the surface of the target block and the horizontal plane in the area of ​​varying floor height. surface It can be obtained from the BIM model or derived through local point cloud computing. Δθ max The maximum permissible surface tilt increment (an empirical value, such as 5°) is used to control smoothness.

[0068] The transition zone must be long enough to ensure a smooth change in surface angle due to variations in floor height, avoiding a noticeable step. The minimum length L of the transition zone... min Determined by geometric relationships, its calculation formula is as follows:

[0069] This formula ensures that, within the transition zone, the change in surface dip angle between adjacent layers will not exceed [a certain value]. .

[0070] Determining the number of transition layers N: The number of layers in the transition zone is determined by both the minimum length and the printing precision. The formula for calculating the number of transition layers N is:

[0071] in, This indicates rounding up, with the average path spacing set to a value, typically slightly smaller than the nozzle diameter. The final value of N is determined by balancing computational efficiency and print quality, ensuring it is an integer.

[0072] 2. Within the transition zone, the gradient height of each transition layer is calculated using linear interpolation or S-curve interpolation algorithms.

[0073] Input parameter: Hstart The height of the initial layer of the transition zone (i.e., H) high or H low H end The height of the final layer of the transition zone is N. N represents the number of layers in the transition zone.

[0074] Linear interpolation is characterized by its simplicity of calculation and uniform transition, but it may produce minute visual seams at the beginning and end of the transition. Specific methods include: For the i-th transition layer (i ranges from 0 to N, a total of N+1 layers), its layer height H i for:

[0075] S-curve interpolation is characterized by a more natural transition, with slow changes at the beginning and end, and faster changes in the middle, effectively avoiding seam problems and resulting in a smoother printed surface. It is commonly implemented using cubic splines or the sigmoid function. A simplified S-curve interpolation formula is as follows:

[0076]

[0077] in, It is a standard S-shaped transition curve function.

[0078] 3. Based on the calculated gradient layer height, the three-dimensional digital model is sliced ​​to generate the slice outline of each transition layer, and the printing path trajectory width and extrusion rate of the layer are adjusted synchronously to maintain the stability of the material deposition cross-sectional area.

[0079] Generate slice outline: For each calculated gradient layer height H i The system slices the model at the corresponding height. This slicing process is the same as for regular layers, but the reference plane changes dynamically, thus generating a specific planar profile for the transition layer.

[0080] The trajectory width and extrusion rate are adjusted synchronously. According to the material deposition model, in order to maintain the stability of the cross-sectional area of ​​the material deposition, the trajectory width W must be adjusted accordingly when the layer height H changes.

[0081] Formula for constant cross-sectional area:

[0082] The value of is an effective value that is determined from the theoretical design value, calibrated by physical experiments, and after satisfying the material properties and equipment constraints.

[0083] Trajectory width adjustment formula: Therefore, the target trajectory width Wi of the i-th transition layer is:

[0084] in, and It refers to the nominal trajectory width and floor height under the standard floor height.

[0085] Extrusion ratio adjustment formula: Based on the material deposition model E = k V W H (where E is the extrusion ratio, V is the printing speed, and k is the material constant), with the printing speed V remaining constant, the extrusion ratio Ei needs to be adjusted synchronously with the new layer height and trajectory width:

[0086] because It is kept constant, therefore the extrusion ratio The printing speed can remain constant within the transition zone, which greatly simplifies the control logic. If the printing speed V changes, it needs to be adjusted proportionally. .

[0087] 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.

[0088] S301. A path optimization algorithm is used to generate a printable path plan for the target layer, consisting of several path segments, where each path segment contains a set of spatial coordinate points; the target layer includes the normal layer and the transition layer in the transition zone.

[0089] Based on the sliced ​​contour (one or more closed polygons) of the target layer (normal layer or transition layer), an equidistant offset algorithm is used to offset one or more inner contour paths inward by a distance of "trajectory width" from the outer contour. The offset process needs to handle the self-intersection problem.

[0090] For the region enclosed by the innermost contour, a path is generated using a fill algorithm such as a zigzag or continuous spiral. The zigzag path is generated by calculating the intersection point with the fill angle.

[0091] Using a heuristic algorithm derived from the Traveling Salesman Problem, all path segments are connected and their order is optimized to minimize the empty travel distance of the printhead.

[0092] Finally, we obtain an ordered set of spatial coordinate points: Path = {P1, P2, ..., P} n}, where each point P i =(x i ,y i ,z layer A line segment between adjacent points constitutes a path segment.

[0093] S302. While generating the set of coordinate points, assign each path segment a trajectory width determined based on the current layer slice outline and filling strategy, and a layer height determined based on the adaptive dynamic layering result.

[0094] The trajectory width is assigned based on the geometric region where the path segment is located. Specifically, this includes: Outer contour path segment: assigns nominal trajectory width W contour To ensure the accuracy of the external dimensions.

[0095] Internal fill path segment: can be assigned a W value slightly larger than the nominal width. infill To improve printing efficiency.

[0096] Transition zone path segment: its trajectory width W transition It is calculated dynamically, and the calculation formula is as follows (see transition area logic):

[0097] in It is the calibrated effective cross-sectional area. It is the height of the transition layer.

[0098] Layer height assignment: For normal layers, all path segments are assigned a fixed layer height H. normal For the transition layer, all path segments are assigned the gradient layer height H calculated by the dynamic layering algorithm. i .

[0099] S303. Preset different speed levels for different types of printing path segments, wherein the outer contour path uses the first speed, and the inner filling path uses the second speed, which is higher than the first speed.

[0100] Different speed settings are preset for different types of path segments: the outer contour path uses the first speed (low speed, such as 30mm / s) to ensure the quality of boundary printing; the inner filling path uses the second speed (high speed, such as 60mm / s) to improve printing efficiency; the transition area path uses a medium speed (such as 45mm / s) and is dynamically adjusted.

[0101] S304. Based on a material deposition model calibrated through physical experiments, calculate the extrusion rate for each path segment; the core concept of the material deposition model is expressed by the following formula: Model calibration: Physical experiments are conducted before actual printing. By printing line segments with different speeds, layer heights, and trajectory widths, the model's compliance is measured, and the material coefficient k is calculated to ensure that the model output matches the actual model.

[0102] For each path segment, its extrusion ratio is calculated using a material deposition model based on its assigned parameters: Extrusion rate = k × printing speed × track width × layer height Where k is the calibrated material coefficient.

[0103] S305. The calculated printing speed and extrusion rate are bound to the set of spatial coordinate points of the corresponding path segment to form a printing instruction with strong coupling between the path and process parameters.

[0104] The resulting print commands (such as G-code) are no longer simple move commands, but rather compound commands with bound parameters. Example command format: G1 X <x i >Y <y i >E <e i >F <f i >; Note: Move to point P i The cumulative extrusion volume up to e i The speed is set to f. i .

[0105] Parameter binding logic: Coordinates (X, Y): Coordinates of the path point from S301.

[0106] Speed ​​F: Fi = 60 (This converts mm / s to millimeters per minute, which is a G-code convention).

[0107] Extrusion quantity E: This is crucial. The extrusion command is not independent, but rather based on the path segment length L. segment and the calculated extrusion rate Accumulate. From point Move to The increase in extrusion volume The calculation formula is:

[0108] in This is the length of the path segment. Total extrusion volume. .

[0109] 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.

[0110] S401. Filter and denoise the 3D point cloud data acquired by real-time scanning, and register it with the theoretical contour obtained from the slice of the 3D digital model through the iterative nearest point algorithm. Calculate the normal deviation of each measurement point to the theoretical surface, and then construct a continuous deviation field covering the entire printing area through the spatial interpolation algorithm.

[0111] After printing the current layer, the line laser scanner integrated into the print head scans the surface of the printed layer to acquire 3D point cloud data containing 50,000 points. First, a statistical filtering algorithm is used to remove outliers whose distance from the neighborhood average exceeds 2 standard deviations; then, Gaussian filtering is applied for smoothing.

[0112] The processed point cloud was registered with the theoretical plane obtained from BIM model slices using an iterative nearest-point algorithm, with the registration error controlled within 0.5mm. The iterative nearest-point algorithm was applied. This algorithm iteratively calculates and finds an optimal rigid body transformation (rotation matrix R and translation vector T) that minimizes the mean square error between corresponding points on the measured point cloud and the theoretical model surface. The objective function is:

[0113] in, These are points in the measured point cloud. It is the point that is closest to the theoretical model.

[0114] After registration, calculate the values ​​for each measured point. The normal deviation Di to the surface of the theoretical model is determined (positive and negative values ​​indicate material accumulation and negative values ​​indicate material loss). Then, Kriging interpolation is used to interpolate these discrete deviation points (pi,Di) into a continuous two-dimensional deviation field D(x,y) covering the entire printed area. Kriging not only provides predicted values ​​but also estimates of the prediction error, outperforming simple linear interpolation.

[0115] S402. Based on the deviation field, the least squares method is used to perform plane fitting on the actual surface of the current printed layer to obtain the best fitting plane; the height correction amount of the reference plane is dynamically determined according to the difference between the height of the best fitting plane and the height of the theoretical plane.

[0116] Ordinary least squares is used to fit a plane to the point cloud data of the current printed layer. Assuming the equation of the fitted plane is z = ax + by + c, the parameters a, b, and c are determined by minimizing the sum of squared deviations of all data points from this plane in the Z direction.

[0117]

[0118] The solved parameter c is the intercept of the best-fit plane on the Z-axis. Reference plane height correction amount. Determined by the following formula:

[0119] in, This is the theoretical reference plane height for the current layer. This correction amount will be directly used to adjust the Z coordinates of all path points in the next layer.

[0120] S403. For each point on the subsequent printing layer path, query the deviation field according to its coordinates to obtain the predicted deviation value D(x,y) at this position; based on the material deposition model, calculate the extrusion rate compensation coefficient according to the predicted deviation value D(x,y), where when D(x,y) is a negative value, the compensation coefficient is greater than 1 to increase the extrusion rate to fill the depression, and when D(x,y) is a positive value, the compensation coefficient is less than 1 to reduce the extrusion rate to avoid scraping the protrusion.

[0121] For each point (x on the next layer path j ,y j ), query in the deviation field D(x,y) constructed in S401 to obtain the predicted deviation value D at this position j =D(x j ,y j ).

[0122] Based on the material deposition model, the idea of a proportional-integral controller is introduced to calculate the extrusion rate compensation coefficient . Its calculation formula is:

[0123] where, is a preset proportional gain coefficient (usually calibrated through experiments, 0<Kp<1), used to control the compensation intensity to avoid over-compensation or oscillation. is the target layer height of the next layer.

[0124] Decision logic: when D j <0 (depression), C j >1, the system will increase the extrusion rate at the path segment where the point is located to fill material; when D j >0 (protrusion), C j <1, the system will reduce the extrusion rate at the path segment where the point is located to avoid further accumulation.

[0125] S404. Integrate the calculated reference plane height correction amount and the extrusion rate compensation coefficient at each path point into the printing instruction of the next layer; the reference plane height correction amount is used to perform superimposed offset on the initial Z-axis reference coordinate of the next layer printing path; the extrusion rate compensation coefficient is used to multiply with the original extrusion rate value of each path point in the next layer printing path to generate the compensated extrusion rate instruction.

[0126] Z-axis reference coordinate correction: When generating the G-code of the next layer, perform global correction on the Z coordinates of all path points: .

[0127] Extrusion rate instruction correction: For the original extrusion rate of each path point (Calculated from step S304) Compensation is performed: .

[0128] Command binding and delivery: The modified Z-coordinate and extrusion rate commands are bound together with the X, Y-coordinate and printing speed F commands to generate the final executable G-code file, which is then delivered to the printer controller for execution.

[0129] In some embodiments, the concrete 3D printing path planning system may include multiple functional modules composed of computer program segments. The computer programs for each program segment in the concrete 3D printing path planning 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) Functionality of path planning in concrete 3D printing.

[0130] In this embodiment, the concrete 3D printing path planning system can be divided into multiple functional modules based on 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.

[0131] The sequence generation module is used to perform structural mechanics analysis based on the three-dimensional digital model of the component to be printed, identify key load-bearing areas, and generate a printing sequence that prioritizes the structural integrity of the key load-bearing areas. The block layering module is used to adaptively and dynamically layer each block in the printing sequence and plan transition areas for areas where the layer thickness changes. The parameter binding module is used to generate the printing path trajectory of each layer and the transition zone, and while generating the trajectory, binds the printing speed and extrusion rate determined based on the material deposition model to each point of the trajectory; The parameter correction module is used to scan the surface morphology of the printed layer in real time during the printing process and compare it with the corresponding theoretical contour to generate deviation data; and dynamically correct the reference plane height and extrusion rate at the path point of the subsequent printed layer based on the deviation data.

[0132] Figure 3The concrete 3D printing path planning method provided in the embodiments of this application can be applied to equipment. Those skilled in the art will understand that the equipment structure involved in the embodiments of this invention does not constitute a limitation on the equipment. The equipment may include more or fewer components than illustrated, or combine certain components, or have different component arrangements. In the embodiments of this invention, the equipment includes, but is not limited to, laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The equipment may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the embodiments of this application described and / or claimed herein.

[0133] The device 300 may include a processor 310, a memory 320, and a communication unit 330. These components communicate via one or more buses. Those skilled in the art will understand that the server structure shown in the figure does not constitute a limitation of the present invention. It may be a bus topology or a star topology, and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0134] The present invention also provides a computer medium, wherein the computer medium may store a program, which, when executed, may include some or all of the steps provided in the embodiments of the present invention. The medium may be a magnetic disk, an optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0135] Those skilled in the art will clearly understand that the techniques in the embodiments of the present invention can be implemented using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a medium such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, or any other medium capable of storing program code. It includes several instructions to cause a computer device (which may be a personal computer, a server, or a second device, network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0136] The same or similar parts between the various embodiments in this specification can be referred to mutually. In particular, the device embodiments are basically similar to the method embodiments, so the description is relatively simple, and the relevant parts can be referred to the description in the method embodiments.

[0137] In the embodiments provided by this invention, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between systems or modules may be electrical, mechanical, or other forms.

[0138] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0139] In addition, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0140] 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 path planning method for concrete 3D printing, characterized in that, include: Structural mechanics analysis is performed based on the three-dimensional digital model of the component to be printed to identify key load-bearing areas, and a printing sequence is generated to prioritize the structural integrity of the key load-bearing areas. Each block in the printing sequence is adaptively and dynamically layered sequentially, and transition areas are planned for regions where the layer thickness changes. Generate printing path trajectories for each layer and transition zone, and while generating the trajectory, bind the printing speed and extrusion rate determined based on the material deposition model to each point of the trajectory; During the printing process, the surface morphology of the printed layer is scanned in real time and compared with the corresponding theoretical contour to generate deviation data; and the reference plane height and extrusion rate at the path point of the subsequent printed layer are dynamically corrected based on the deviation data. The blocks in the printing sequence are adaptively and dynamically layered sequentially, and transition areas are planned for regions with varying layer thicknesses, including: For each target block in the printing sequence, the geometric features of the target block are identified, and the geometric features include at least overhanging regions, high curvature regions, and flat regions; Based on the identified geometric features, a layer height constraint map of the target block is generated, wherein the layer height constraint map marks the maximum allowable layer height of different areas of the block based on geometric precision; Using the aforementioned layer height constraint map as the primary constraint, and combined with the interlayer bonding strength constraint of the material, the target block is sliced ​​from bottom to top, and a maximum layer height is dynamically determined for each layer under all constraint conditions. When the height difference between two adjacent layers exceeds a preset threshold, a transition zone with a gradual change in height is generated between them. Structural mechanics analysis is performed based on the 3D digital model of the component to be printed to identify key load-bearing areas. Based on this, a printing sequence is generated that prioritizes the structural integrity of these key load-bearing areas, including: Finite element analysis is performed on the three-dimensional digital model of the component to be printed, and the stress distribution inside the model is obtained by solving the problem. Based on the stress distribution, key load-bearing areas with stress exceeding a preset threshold are identified; Based on the distribution of the key load-bearing areas, the entire printed component is divided into multiple sub-blocks, and each sub-block is assigned a printing priority based on its stress level and structural importance. Based on the printing priority, the printing order of each sub-block is determined, and the printing sequence is generated.

2. The method according to claim 1, characterized in that, When the height difference between two adjacent floors exceeds a preset threshold, a gradual transition zone with varying floor heights is generated between them, including: Based on the height difference and the surface geometric features of the target block in the height variation region, the length of the transition zone and the number of transition layers contained therein are dynamically calculated. Within the transition zone, linear interpolation or S-curve interpolation algorithms are used to calculate the gradient height of each transition layer. The three-dimensional digital model is sliced ​​based on the calculated gradient layer height to generate the slice outline of each transition layer. The width of the printing path trajectory and the extrusion rate of the layer are adjusted simultaneously to maintain the stability of the material deposition cross-sectional area.

3. The method according to claim 1, characterized in that, Generate printing path trajectories for each layer and transition zone, and simultaneously bind the printing speed and extrusion rate determined based on the material deposition model to each point of the trajectory, including: A path optimization algorithm is used to generate a printable path plan for the target layer, consisting of several path segments, where each path segment contains a set of spatial coordinate points; the target layer includes the normal layer and the transition layer in the transition zone. While generating the set of coordinate points, each path segment is assigned a trajectory width determined based on the current layer slice outline and filling strategy, and a layer height determined based on the adaptive dynamic layering results. Different speed levels are preset for different types of printing path segments. The outer contour path uses the first speed, and the inner filling path uses a second speed that is higher than the first speed. Based on a material deposition model calibrated through physical experiments, the extrusion rate is calculated for each path segment; the core concept of the material deposition model is expressed by the following formula: Extrusion rate = k × printing speed × track width × layer height Where k is the calibrated material coefficient; The calculated printing speed and extrusion rate are bound to the corresponding set of spatial coordinate points of the path segment, forming a printing instruction that strongly couples the path with the process parameters.

4. The method according to claim 1, characterized in that, The surface morphology of the printed layer is scanned in real time and compared with the corresponding theoretical contour to generate deviation data; and the reference plane height and extrusion rate at path points of subsequent printed layers are dynamically corrected based on the deviation data, including: The 3D point cloud data acquired by real-time scanning is filtered and denoised, and then registered with the theoretical contour obtained from the slice of the 3D digital model through the iterative nearest point algorithm. The normal deviation of each measurement point to the theoretical surface is calculated, and then a continuous deviation field covering the entire printing area is constructed through the spatial interpolation algorithm. Based on the deviation field, the least squares method is used to perform plane fitting on the actual surface of the current printed layer to obtain the best fitting plane; the reference plane height correction amount is dynamically determined according to the difference between the height of the best fitting plane and the theoretical plane height. For each point on the subsequent printing layer path, the deviation field is queried according to its coordinates to obtain the predicted deviation value D(x,y) at that position; based on the material deposition model, the extrusion rate compensation coefficient is calculated according to the predicted deviation value D(x,y). When D(x,y) is negative, the compensation coefficient is greater than 1 to increase the extrusion rate to fill the depression, and when D(x,y) is positive, the compensation coefficient is less than 1 to reduce the extrusion rate to avoid scratching the protrusion. The calculated reference plane height correction amount and the extrusion rate compensation coefficient at each path point are integrated into the printing command of the next layer; the reference plane height correction amount is used to superimpose and offset the initial Z-axis reference coordinate of the printing path of the next layer; the extrusion rate compensation coefficient is used to multiply with the original extrusion rate value of each path point in the printing path of the next layer to generate the compensated extrusion rate command.

5. A concrete 3D printing path planning system, characterized in that, include: The sequence generation module is used to perform structural mechanics analysis based on the three-dimensional digital model of the component to be printed, identify key load-bearing areas, and generate a printing sequence that prioritizes the structural integrity of the key load-bearing areas. The block layering module is used to adaptively and dynamically layer each block in the printing sequence and plan transition areas for areas where the layer thickness changes. The parameter binding module is used to generate the printing path trajectory of each layer and the transition zone, and while generating the trajectory, binds the printing speed and extrusion rate determined based on the material deposition model to each point of the trajectory; The parameter correction module is used to scan the surface morphology of the printed layer in real time during the printing process, compare it with the corresponding theoretical contour to generate deviation data, and dynamically correct the reference plane height and extrusion rate at the path point of the subsequent printed layer based on the deviation data. The blocks in the printing sequence are adaptively and dynamically layered sequentially, and transition areas are planned for regions with varying layer thicknesses, including: For each target block in the printing sequence, the geometric features of the target block are identified, and the geometric features include at least overhanging regions, high curvature regions, and flat regions; Based on the identified geometric features, a layer height constraint map of the target block is generated, wherein the layer height constraint map marks the maximum allowable layer height of different areas of the block based on geometric precision; Using the aforementioned layer height constraint map as the primary constraint, and combined with the interlayer bonding strength constraint of the material, the target block is sliced ​​from bottom to top, and a maximum layer height is dynamically determined for each layer under all constraint conditions. When the height difference between two adjacent layers exceeds a preset threshold, a transition zone with a gradual change in height is generated between them. Structural mechanics analysis is performed based on the 3D digital model of the component to be printed to identify key load-bearing areas. Based on this, a printing sequence is generated that prioritizes the structural integrity of these key load-bearing areas, including: Finite element analysis is performed on the three-dimensional digital model of the component to be printed, and the stress distribution inside the model is obtained by solving the problem. Based on the stress distribution, key load-bearing areas with stress exceeding a preset threshold are identified; Based on the distribution of the key load-bearing areas, the entire printed component is divided into multiple sub-blocks, and each sub-block is assigned a printing priority based on its stress level and structural importance. Based on the printing priority, the printing order of each sub-block is determined, and the printing sequence is generated.

6. A concrete 3D printing path planning device, characterized in that, include: Memory for storing concrete 3D printing path planning programs; A processor, configured to implement the steps of the concrete 3D printing path planning method as described in any one of claims 1-4 when executing the concrete 3D printing path planning program.

7. A computer-readable medium storing a computer program, characterized in that, The readable medium stores a concrete 3D printing path planning program, which, when executed by a processor, implements the steps of the concrete 3D printing path planning method as described in any one of claims 1-4.

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