Dual-device collaborative 3D printing method and system

Abstract

The present disclosure relates to the field of 3D printing, and particularly to a dual-device collaborative 3D printing method and system. The method comprises: generating mortise-and-tenon polygons at an interface between collaboratively printed components; generating sample points by equally dividing the geometric boundary of an irregular structure; generating Voronoi polygons using the sample points; sorting and connecting the Voronoi polygons in the irregular structure in series; performing a global shift on the series-connected Voronoi polygons and mortise-and-tenon polygons; and generating a printing path adapted to dual-device collaborative 3D printing.

Description

Dual-device collaborative 3D printing method and system

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to Chinese Patent Application No. 202410647761.X, filed on May 23, 2024, entitled “Dual-device collaborative 3D printing method and system” to Tsinghua University. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of 3D printing, and in particular, to a dual-device collaborative 3D printing method and system. BACKGROUND

[0004] 3D printing concrete technology is a new intelligent construction method, which realizes the construction of building structures by extruding rapid-setting concrete using printing devices such as mechanical arms and gantries. This technology helps to reduce the labor demand in the construction process and improve the intelligent level of the construction industry, but it is still difficult to realize the construction of large-scale buildings and structures with holes due to the following reasons.

[0005] Firstly, the building size that can be realized by 3D printing technology is limited by the mobility and printing range of the printing device, so the building planar area that can be printed by a single device is very limited. The common method in the industry is to use movable devices or moving tracks to improve the mobility of the printing device, but these additional devices can only realize movement in a single direction and cannot expand the working range of the device in the entire planar space.

[0006] Secondly, 3D printing concrete technology needs to meet the continuity requirement of the printing path, i.e., the printing path of each slice needs to form a single continuous closed loop to ensure that the concrete can be smoothly and continuously extruded. However, the structure with holes destroys the continuity of the printing path. If you want to print a hole structure through a single device, you need to complete the printing work on one side of the hole structure in each layer, then stop extruding the concrete, move the printing head to the other side of the hole, and then continue to extrude. This operation process will cause obvious defects (such as excessive or insufficient material extrusion) at the nodes where the concrete stops and re-extrudes, affecting the quality of printing.

[0007] In summary, how to realize large-scale, hole-containing buildings or structures is an urgent field to be explored in current 3D printing concrete technology.

[0008] Device collaborative printing helps to solve the problem of the printability of large-scale, hole-containing concrete structures, but the current device collaborative printing method still has three main problems: weak connection, easy collision, and difficulty in changing.

[0009] Firstly, in the current collaborative printing method used in the field of 3D printing concrete, the point-type joint is used at the joint of the printing components of the two printing devices, that is, the printing paths of the two devices do not intersect or overlap, but only approach each other at specific points. This path planning method helps to minimize the collision probability of the printing devices, but the point-type joint method leads to a very weak connection between the two printing components. Therefore, the components printed by this method cannot meet the structural requirements in actual engineering.

[0010] Secondly, the current printing path planning method for device collaboration has a high collision probability. In architectural engineering, concrete structures need to include external surfaces and internal supports. In order to complete these structures in one printing process, the printing path needs to be folded back multiple times at both ends of the slice. In the same unit time, the more times the path is folded back, the more collision risks are increased.

[0011] Thirdly, architectural 3D printing needs to meet the requirements of actual use functions and needs to be optimized through structure to reduce material consumption and carbon emissions in the construction process. These functional requirements and optimization methods often result in many non-standard and hole-bearing structural components in the building, and the topological relationship of each layer of the slice changes constantly during 3D printing, which requires the path generated by each layer of the slice to adapt to the changing slice boundary, which brings great difficulty to the writing of the printing path.

[0012] In summary, how to design a printing path that can improve the engagement between the printing components of the two devices, ensure the smoothness and safety of the printing process, and match the topology of complex structures is a problem that has not been solved in the current device collaborative 3D printing concrete technology. SUMMARY

[0013] The present disclosure provides a double-device collaborative 3D printing method and system to solve the problems of weak connection, easy collision and difficulty in changing in the current device collaborative printing method.

[0014] The first aspect embodiment of the present disclosure provides a double-device collaborative 3D printing method, comprising the following steps:

[0015] Generating a 3D printing model of a structure to be printed, separating and slicing the 3D printing model to obtain a first graphical boundary line for printing by a first mechanical arm and a second graphical boundary line for printing by a second mechanical arm;

[0016] Extracting the boundary line segment of the intersection position of the first graphical boundary line and the second graphical boundary line, converting the boundary line segment into a polygon, dividing the polygon into two polygons, and then distributing the two polygons to the first mechanical arm and the second mechanical arm alternately according to the printing layer sequence to form a mortise and tenon polygon.

[0017] dividing the first graphic boundary line and the second graphic boundary line into m sample points, generating m Thiessen polygons associated with the m sample points, sorting the m sample points, and concatenating the Thiessen polygons corresponding to the sample points and the assigned mortise-tenon polygons one by one in the manner of a median line;

[0018] offsetting the concatenated Thiessen polygons and mortise-tenon polygons as a whole by half the width of the printing line to obtain the printing path of the first mechanical arm and the second mechanical arm.

[0019] In some embodiments, the 3D printing model is separated and sliced to obtain a first graphic boundary line for printing by the first mechanical arm and a second graphic boundary line for printing by the second mechanical arm, including:

[0020] The 3D printing model is separated to obtain a first model for printing by the first mechanical arm and a second model for printing by the second mechanical arm, and the first model and the second model are sliced to obtain a first graphic boundary line of the first model and a second graphic boundary line of the second model.

[0021] In some embodiments, the first graphic boundary line and the second graphic boundary line are divided into m sample points, m Thiessen polygons associated with the m sample points are generated using the m sample points, the m sample points are sorted, and the sorted results are concatenated one by one in the manner of a median line, including the following steps:

[0022] unifying the starting point positions of the first graphic boundary line and the second graphic boundary line, dividing the first graphic boundary line and the second graphic boundary line into m segments, generating m sample points, generating a Thiessen polygon within the boundary line using the m sample points, and numbering the Thiessen polygon, with the number of the Thiessen polygon being consistent with the number of the sample point generating the Thiessen polygon;

[0023] For all printing layers, an arbitrarily numbered sample point is selected as a starting search point, and a search is performed within a ±45° range in the negative direction of the Y axis of the starting search point to find a sample point that satisfies a predetermined connection condition, and after each search, a line is drawn from the starting search point to the sample point that satisfies the predetermined connection condition;

[0024] The sample point that satisfies the predetermined connection condition is used as a new search point to continue searching until there is no sample point that satisfies the predetermined connection condition, and all the lines generated in the search process are combined into a continuous multi-segment line;

[0025] finding a sample point satisfying the preset starting condition in the sample points of the same print layer which are not searched, as a starting search point of a new round of connection, starting the new round of search from the starting search point in the negative direction of the Y axis, finding a sample point satisfying the preset connection condition, and generating the continuous polyline;

[0026] repeating the search process multiple times until all sample points of the current print layer are searched and a new continuous polyline cannot be generated;

[0027] connecting the vertex of the continuous polyline in the positive direction of the Y axis with the nearest sample point on the adjacent continuous polyline to form all bridging polylines between the continuous polylines;

[0028] mapping the connection relationship of all sample points on the continuous polylines and the bridging polylines to the Thiessen polygons corresponding to the sample points, and generating a perpendicular line at the intersection of the Thiessen polygons having the connection relationship;

[0029] generating the same perpendicular line as the previous step at the intersection of the mortise-tenon polygon and the adjacent Thiessen polygon.

[0030] In some embodiments, the preset connection condition is that the absolute value of the slope of the connection line of the sample point and the search point is maximum, and the Thiessen polygon corresponding to the sample point is adjacent to the Thiessen polygon corresponding to the search point.

[0031] In some embodiments, the preset starting condition is that there is no sample point satisfying the preset connection condition in the sample points of the same print layer, and there is a sample point not searched in the current print layer, then in all remaining sample points, the point with the maximum value of (y-k·x) of the coordinates is found as the starting search point of a new round of connection, wherein k is the slope.

[0032] The second aspect embodiment of the present disclosure provides a dual-device cooperative 3D printing system, comprising: a first mechanical arm and a second mechanical arm; a generation module configured to generate a 3D printing model of a structure to be printed, separate and slice the 3D printing model to obtain a first graphic boundary line for printing by the first mechanical arm and a second graphic boundary line for printing by the second mechanical arm; an extraction module configured to extract a boundary line segment at an intersection position of the first graphic boundary line and the second graphic boundary line, convert the boundary line segment into a polygon, and after dividing the polygon into two polygons, alternately distribute the two polygons to the first mechanical arm and the second mechanical arm in the order of printing layers to form a mortise and tenon polygon; a connection module configured to divide the first graphic boundary line and the second graphic boundary line into m sample points, generate m Thiessen polygons associated with the m sample points, sort the m sample points, and sequentially connect the Thiessen polygons corresponding to the sample points and the assigned mortise and tenon polygons in the manner of a median line; and a printing module configured to offset the Thiessen polygons and the mortise and tenon polygons after the connection in the manner of a median line by half the printing line width to obtain a printing path of the first mechanical arm and the second mechanical arm.

[0033] In some embodiments, the generation module is further configured to separate the 3D printing model to obtain a first model for printing by the first mechanical arm and a second model for printing by the second mechanical arm, and slice the first model and the second model to obtain a first graphic boundary line of the first model and a second graphic boundary line of the second model.

[0034] In some embodiments, the connection module is specifically configured to:

[0035] unify the starting point positions of the first graphic boundary line and the second graphic boundary line, divide the first graphic boundary line and the second graphic boundary line into m segments, generate m sample points, generate a Thiessen polygon within the boundary line by using the m sample points, and number the Thiessen polygon, wherein the number of the Thiessen polygon is consistent with the number of the sample point generating the Thiessen polygon;

[0036] for all printing layers, select an arbitrary sample point with the same number as a starting search point, search in the ±45° range in the negative direction of the Y axis of the starting search point to find a sample point satisfying a preset connection condition, and after each search, connect the starting search point and the sample point satisfying the preset connection condition;

[0037] continue searching with the sample point satisfying the preset connection condition as a new search point until there is no sample point satisfying the preset connection condition, and combine all the lines generated in the searching process into a continuous multi-segment line;

[0038] find a sample point satisfying the preset starting condition in the sample points of the same print layer which are not searched, as a starting search point of a new round of connection, start a new round of search along the negative direction of the Y axis from the starting search point, find a sample point satisfying the preset connection condition, and generate the continuous polyline;

[0039] repeat the search process multiple times until all sample points of the current print layer have been searched and a new continuous polyline cannot be generated;

[0040] connect the vertex of all continuous polylines in the positive direction of the Y axis with the nearest sample point on the adjacent continuous polyline to form all bridging polylines between the continuous polylines;

[0041] map the connection relationship of all sample points on the continuous polylines and the bridging polylines to the Thiessen polygons corresponding to the sample points, and generate perpendicular bisectors at the intersection lines of the Thiessen polygons having the connection relationship;

[0042] generate the same perpendicular bisectors as in the previous step at the intersection lines of the mortise-tenon polygons and the adjacent Thiessen polygons.

[0043] In some embodiments, the preset connection condition is that the absolute value of the slope of the connection line of the sample point and the search point is maximum, and the Thiessen polygon corresponding to the sample point is adjacent to the Thiessen polygon corresponding to the search point.

[0044] In some embodiments, the preset starting condition is that there is no sample point satisfying the preset connection condition in the sample points of the same print layer, and there is a sample point not searched in the current print layer, then in all remaining sample points, find the point with the maximum value of (y-k·x) of the coordinates as the starting search point of a new round of connection, wherein k is the slope.

[0045] The double-device cooperative 3D printing method and system provided by the embodiments of the present disclosure have the following beneficial effects:

[0046] 1. From the dimension of structure generation, the method enhances the occlusion mode between the two printed components, so that the shared printing area of the two mechanical arms can achieve better connection, ensuring the strength of the cooperative printed components.

[0047] 2. From the perspective of path planning, the method ensures that the printing path only makes a path turn in each slice, minimizing the collision probability of the printing device. This path planning method can also be used in 3D printing of other materials.

[0048] 3. From the perspective of computational cost, the method uses a local path generation method instead of a global path generation method to effectively reduce the printing path generation complexity of irregular graphics and improve the efficiency of printing line generation.

[0049] 4. From the actual construction dimension, the method solves the device coordination problem of 3D printing large building components, and promotes the application of device coordination printing in actual building engineering.

[0050] Additional aspects and advantages of the present disclosure will be described in part in the description that follows, and in part will become apparent to those skilled in the art from the description, or by practicing the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0051] The above and / or additional aspects and advantages of the present disclosure will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

[0052] Fig. 1 is a flow chart of a double-device coordinated 3D printing method according to an embodiment of the present disclosure;

[0053] Fig. 2 is a printing process of double-arm coordinated printing according to an embodiment of the present disclosure;

[0054] Fig. 3 is a schematic diagram of a printing path generation process according to an embodiment of the present disclosure;

[0055] Fig. 4 is a structural component printed according to an embodiment of the present disclosure;

[0056] Fig. 5 is another structural component printed according to an embodiment of the present disclosure;

[0057] Fig. 6 is still another structural component printed according to an embodiment of the present disclosure;

[0058] Fig. 7 is a block schematic diagram of a double-device coordinated 3D printing system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0059] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are intended to explain the present disclosure, and cannot be understood as a limitation of the present disclosure.

[0060] Fig. 1 is a flow chart of a double-device coordinated 3D printing method according to an embodiment of the present disclosure.

[0061] As shown in Fig. 1, the double-device coordinated 3D printing method includes the following steps:

[0062] In step S101, a 3D printing model of a structure to be printed is generated, and the 3D printing model is separated and sliced to obtain a first graphic boundary line for printing by a first mechanical arm and a second graphic boundary line for printing by a second mechanical arm.

[0063] In the embodiments of the present disclosure, first, the 3D printing model is divided to obtain a first model for printing by a first mechanical arm and a second model for printing by a second mechanical arm, and second, the first model and the second model are sliced to obtain a first graphic boundary line of the first model and a second graphic boundary line of the second model.

[0064] In step S102, a boundary line segment at the intersection position of the first graphic boundary line and the second graphic boundary line is extracted, the boundary line segment is converted into a polygon, the polygon is equally divided into two polygons, and the two polygons are alternately distributed to the first mechanical arm and the second mechanical arm in the order of printing layers to form a mortise and tenon polygon.

[0065] In the embodiments of the present disclosure, at the junction of the first model and the second model, the graphic boundary line segment at the junction is converted into a polygon, which can be a hexagon or other symmetrical polygon, and the converted polygon is equally divided into two identical polygons.

[0066] The present disclosure alternately distributes the printing units of the polygon to different printing devices, so that the printing members of the two devices are overlapped and engaged layer by layer, thereby ensuring the structural strength of the cooperative printing members.

[0067] In step S103, the first graphic boundary line and the second graphic boundary line are equally divided into m sample points, m Thiessen polygons associated with the m sample points are generated by using the m sample points, the m sample points are sorted, and the Thiessen polygons corresponding to the sample points and the assigned mortise and tenon polygons are sequentially connected in the manner of median line according to the sorting results.

[0068] In the embodiments of the present disclosure, step S103 specifically includes the following steps:

[0069] The starting point positions of the first graphic boundary line and the second graphic boundary line are unified, the first graphic boundary line and the second graphic boundary line are equally divided into m segments, m sample points are generated, Thiessen polygons within the boundary line are generated by using the m sample points, and the Thiessen polygons are numbered, and the numbering of the Thiessen polygons is consistent with the numbering of the sample points for generating the Thiessen polygons;

[0070] For all printing layers, an arbitrary sample point with the same number is selected as a starting search point, and a search is performed within a ±45° range in the negative direction of the Y axis of the starting search point to find a sample point satisfying a preset connection condition, and after each search, a line is connected between the starting search point and the sample point satisfying the preset connection condition;

[0071] The sample point satisfying the preset connection condition is taken as a new search point to continue the search until there is no sample point satisfying the preset connection condition, and all the lines generated in the search process are combined into a continuous multi-segment line.

[0072] find a sample point satisfying the preset starting condition in the sample points not searched in the same printing layer as the starting search point of the new round of connection, start a new round of search along the negative direction of the Y axis from the starting search point, find a sample point satisfying the preset connection condition, and generate the continuous polyline;

[0073] repeat the search process multiple times until all sample points of the current printing layer have been searched and a new continuous polyline cannot be generated;

[0074] connect the vertex of the continuous polyline in the positive direction of the Y axis to the nearest sample point on the adjacent continuous polyline to form all the bridging polylines between the continuous polylines;

[0075] map the connection relationship of all sample points on the continuous polylines and the bridging polylines to the Thiessen polygons corresponding to the sample points, and generate the perpendicular bisector at the intersection of the Thiessen polygons having the connection relationship;

[0076] generate the same perpendicular bisector as in the previous step at the intersection of the mortise-and-tenon polygon and the adjacent Thiessen polygon.

[0077] In an embodiment of the present disclosure, the preset connection condition is that the absolute value of the slope of the connection line of the sample point and the search point is maximum, and the Thiessen polygon corresponding to the sample point is adjacent to the Thiessen polygon corresponding to the search point.

[0078] In an embodiment of the present disclosure, the preset starting condition is that there is no sample point satisfying the preset connection condition in the sample points of the same printing layer, and there is a sample point not searched in the current printing layer, then in all the remaining sample points, find the point with the maximum value of (y-kx) of the coordinates as the starting search point of the new round of connection, wherein k is the slope.

[0079] The present disclosure generates sample points by the method of equal division of irregular geometric boundaries, and then generates Thiessen polygons using these sample points. The Thiessen polygons generated by this method can adapt to the topological changes of complex hole structures, avoid the problem of sudden change of printing path of adjacent printing layers, ensure the continuity of the printing path in the Z axis direction (i.e. the printing direction), and make the printing path meet the self-supporting requirement of concrete 3D printing.

[0080] By searching and sorting the sample points in the Thiessen polygons, the search results can be used to connect all the Thiessen polygons and mortise-and-tenon polygons in the irregular figure.

[0081] In step S104, the whole offset of the series-connected Tessellation polygon and mortise-tenon polygon is performed by half of the printing line width, to obtain the printing paths of the first mechanical arm and the second mechanical arm, both of which only make one turn in the X-axis direction of the figure, so as to meet the path continuity requirement of 3D printing and minimize the collision risk of any irregular figure in the printing process.

[0082] Fig. 2 shows the printing path generation process of one printing layer of the double-arm cooperative printing, and Fig. 3 shows the printing path generation process of the whole figure. In combination of Figs. 2 and 3, the 3D printing method of the present disclosure is described in detail. In Fig. 3, No. 1 is the printing range of the left mechanical arm, No. 2 is the printing range of the right mechanical arm, No. 3 and No. 4 are mortise-tenon polygons, i.e., the alternately printed areas of the left mechanical arm and the right mechanical arm, the current printing layer is printed by the left mechanical arm, and the next layer is printed by the right mechanical arm, No. 5 is a sample point for generating a Tessellation polygon, No. 6 is a sample point designated as a starting search point, No. 7 is a sample point designated as a search point after the start of the search process, No. 8 is a continuous polyline in step 6, No. 9 is a bridging polyline in step 7, and No. 10 is a perpendicular line in step 8.

[0083] In one specific embodiment of the present disclosure, the double-device cooperative 3D printing method comprises the following steps:

[0084] Step 1: generating a structure model for double-arm cooperative printing by using computer-aided design software, and dividing the model into two independent parts as the printing component models of the two mechanical arms according to the actual printing requirements and the working range of the mechanical arms.

[0085] Step 2-1: slicing the component model according to the actual required printing layer height, generating a figure boundary line, and separately extracting the line segments of the boundary line at the intersection position of the two components, and converting the line segments into hexagons (as shown in Fig. 3(a)).

[0086] Step 2-2: dividing the hexagons into two parts (polygons 3 and 4 in Fig. 3(a)), and then alternately distributing the two polygons to the two mechanical arms along the printing layer sequence to form mortise-tenon polygons. For example, in the printing layer shown in Fig. 3(a), polygon 3 is distributed to the left mechanical arm, and polygon 4 is distributed to the right mechanical arm, while in the next printing layer, polygon 3 will be distributed to the right mechanical arm, and polygon 4 will be distributed to the left mechanical arm. This alternately distributing process can make the printing lines of the two mechanical arms overlap and engage layer by layer to form a continuous whole.

[0087] Step 3, unify the starting point position of the boundary line, and divide the printing line into m segments, generate m sample points, and use the same numbering logic to number the sample points on each layer of the printing line. Then, generate the Thiessen polygons within the boundary line by means of these sample points (as shown in (b) of FIG. 3), and number the Thiessen polygons, which is consistent with the sample point numbering.

[0088] Step 4-1, for all printing layers, select an arbitrary control point with the same number as the search point, and search within the ±45° range in the negative direction of the Y axis at this point (as shown in (c) of FIG. 3, the value of the search range can be adjusted according to actual needs, if the Thiessen polygons are many and dense, it is recommended to reduce the search range, and vice versa). The search process needs to find sample points that meet the following two conditions:

[0089] Condition 1: the absolute value of the slope of the line connecting the sample point and the search point is maximum;

[0090] Condition 2: the Thiessen polygon corresponding to the sample point is adjacent to the Thiessen polygon corresponding to the search point.

[0091] Step 4-2, after each search, connect the search point and the sample point that meets the condition.

[0092] Step 5, introduce a condition judgment, if there is a sample point that meets the condition in step 4, take the sample point as a new search point, and repeat step 4. If there is no sample point that meets the condition, combine all the lines generated in the search process into a continuous multi-segment line, and then enter step 6.

[0093] Step 6, introduce a condition judgment, if all sample points of the printing layer have been searched and no new line can be generated, enter step 7, if there are still points that have not been searched, find the point with the maximum (y-kx) value in the remaining all sample points as the starting search point of the new round of line (k is the slope, generally take 1, can be adjusted according to the actual topological configuration of the figure), and repeat steps 4 to 6, until all control points are searched. Each time step 6 is repeated, a continuous multi-segment line is generated, which is connected point by point along the negative direction of the Y axis of the figure (as shown in (d) of FIG. 3).

[0094] Step 7, connect the vertices of all continuous multi-segment lines recorded in step 6 with the nearest sample points on their adjacent multi-segment lines to form all the bridge multi-segment lines between the continuous multi-segment lines (as shown in (d) of FIG. 3).

[0095] Step 8, since there is a one-to-one correspondence between the sample points and the Thiessen polygons, by recording the starting point number of all connecting lines, the midlines with the same connecting relationship can be generated on the intersection line of the two Thiessen polygons corresponding to the starting point, and these midlines can be used to connect all the Thiessen polygons into a whole (as shown in (e) of FIG. 3). At the same time, according to the distribution method in step 2-2, a segment of the midline connected with the printing range to which it belongs can be generated on the mortise and tenon polygon distributed at the junction.

[0096] Step 9, integrating all the midlines, Thiessen polygons and distributed mortise and tenon polygons into a curve set, and offsetting the whole by half the printing line width, the printing line that meets the one-way round trip requirement and can be used for device cooperation can be obtained (as shown in (f) of FIG. 3).

[0097] Step 10, verifying the printability of the printing line. Starting from the starting points of the two paths, taking the printing line equal division distance d of the generated G code as the step, the distance between the printing positions at the same time on the two printing lines is calculated step by step, and if the distance is shorter than the distance between the print heads, it means that the model cannot be realized by double-arm cooperation, and needs to return to step 1 to adjust the design scheme, or return to step 3 to increase the subdivision number m of the boundary line, until the printing line meets the obstacle avoidance requirement.

[0098] Step 11, combining the device running parameters, converting the printing line into G code that can be used for 3D printing, assigning it to two printing devices, and performing 3D printing.

[0099] The process of the above embodiment generates the following three large-scale concrete structural members with holes, as shown in FIGS. 4, 5 and 6. In FIGS. 4, 5 and 6, (a) is the input graph, (b) is the printing line, and (c) is a schematic of the printing effect. Among them, FIG. 4 is the column head joint member of two concrete columns, the joint is gradually enlarged and integrated into one, forming a door-shaped space. FIG. 5 is the prototype of a branch support structure, the bottom is an integral whole, which branches in the middle of the structure and respectively cantilevers outward, and finally forms a larger support plane at the top than the bottom. This type of structure helps to reduce the material consumption of large cantilever members. FIG. 6 is a non-standard concrete support structure. This embodiment has holes in both the vertical and horizontal directions. This type of structure often appears in the structures obtained by topology optimization. For the three embodiments, the technical scheme proposed in the present disclosure can be used to generate the printing path and used for double-device cooperative 3D printing.

[0100] The double-device collaborative 3D printing method of the present disclosure proposes a method for sorting and concatenating the Thiessen polygons inside irregular structures, and uses the method to generate printing paths suitable for double-device collaborative 3D printing. These printing paths can satisfy the condition that the printing device only makes one U-turn motion in each printing layer, minimize the probability of collision in the device collaborative printing process, enable large-scale, hole-containing concrete structures to be printable, and improve the application scenarios and intelligent level of 3D printing concrete technology.

[0101] The double-device collaborative 3D printing method of the present disclosure can generate layer-by-layer overlapping polygonal structures at the junctions of the collaborative printed components, which helps to improve the engagement between the two printed components and solve the problem of weak connection between the collaborative 3D printed components. At the same time, the present disclosure makes the support structures in the concrete components as perpendicular to the graphic boundary as possible, which enhances the overall structural strength of the collaborative 3D printed components and improves the potential of the collaborative printed components for use in actual construction engineering.

[0102] The double-device collaborative 3D printing method of the present disclosure uses the equidivision points on the slice boundary as the basis for generating internal polygonal support structures. This enables the printing lines generated by the present disclosure to meet the topological changes of hole-containing components in the Z-axis direction (i.e., the printing direction), maintaining the continuity of the upper and lower layer printing paths in configuration and position. This solves the problem of difficult generation of complex graphic printing paths and reduces the complexity of 3D printing technology path programming.

[0103] The double-device collaborative 3D printing method of the present disclosure provides a workflow for automatically generating printing paths according to target graphics and evaluating the printability of the paths. This method can be applied to small 3D printing devices such as robotic arms and drones, as well as collaborative 3D printing of other materials such as clay, polylactic acid, and recyclable plastics, and has wide application value.

[0104] Next, the double-device collaborative 3D printing system proposed according to the embodiments of the present disclosure is described with reference to the accompanying drawings.

[0105] FIG. 7 is a block schematic diagram of the double-device collaborative 3D printing system of the embodiments of the present disclosure.

[0106] As shown in FIG. 7, the double-device collaborative 3D printing system 10 includes a first robotic arm and a second robotic arm, a generation module 100, an extraction module 200, a connection module 300, and a printing module 400.

[0107] The generation module 100 is configured to generate a 3D printing model of a structure to be printed, separate and slice the 3D printing model to obtain a first graphic boundary line for printing by the first mechanical arm and a second graphic boundary line for printing by the second mechanical arm. The extraction module 200 is configured to extract a boundary line segment at an intersection position of the first graphic boundary line and the second graphic boundary line, convert the boundary line segment into a polygon, and alternately allocate two polygons obtained by equally dividing the polygon to the first mechanical arm and the second mechanical arm in the order of printing layers to form a mortise-and-tenon polygon. The connection module 300 is configured to equally divide the first graphic boundary line and the second graphic boundary line into m sample points, generate m Thiessen polygons associated with the m sample points, sort the m sample points, and sequentially connect the Thiessen polygons corresponding to the sample points and the mortise-and-tenon polygons allocated thereto in the manner of a median line. The printing module 400 is configured to offset the Thiessen polygons and the mortise-and-tenon polygons connected in a whole after printing in a line width of one-half to obtain a printing path of the first mechanical arm and the second mechanical arm.

[0108] Optionally, in an embodiment of the present disclosure, the generation module 100 is further configured to separate the 3D printing model to obtain a first model for printing by the first mechanical arm and a second model for printing by the second mechanical arm, and slice the first model and the second model to obtain a first graphic boundary line of the first model and a second graphic boundary line of the second model.

[0109] Optionally, in an embodiment of the present disclosure, the connection module 300 is specifically configured to:

[0110] unify a starting point position of the first graphic boundary line and the second graphic boundary line, equally divide the first graphic boundary line and the second graphic boundary line into m segments, generate m sample points, generate a Thiessen polygon in the boundary line by using the m sample points, and number the Thiessen polygon, wherein the number of the Thiessen polygon is consistent with the number of the sample point generating the Thiessen polygon;

[0111] for all printing layers, selecting an arbitrary sample point with the same number as a starting search point, searching in a ±45° range in a negative direction of the Y axis of the starting search point to find a sample point satisfying a preset connection condition, and connecting the starting search point and the sample point satisfying the preset connection condition after each search;

[0112] continuing to search by taking the sample point satisfying the preset connection condition as a new search point until there is no sample point satisfying the preset connection condition, and merging all lines generated in the searching process into a continuous multi-segment line;

[0113] find a sample point satisfying the preset starting condition in the sample points not searched in the same printing layer as the starting search point of the new round of connection, start a new round of search along the negative direction of the Y axis from the starting search point, find a sample point satisfying the preset connection condition, and generate the continuous polyline;

[0114] repeat the search process multiple times until all sample points in the current printing layer have been searched and a new continuous polyline cannot be generated;

[0115] connect the vertex of all continuous polylines in the positive direction of the Y axis to the nearest sample point on the adjacent continuous polyline to form all bridging polylines between the continuous polylines;

[0116] map the connection relationship of all sample points on the continuous polylines and the bridging polylines to the Thiessen polygons corresponding to the sample points, and generate the perpendicular bisector at the intersection of the Thiessen polygons having the connection relationship;

[0117] generate the same perpendicular bisector as in the previous step at the intersection of the mortise-tenon polygon and the adjacent Thiessen polygon.

[0118] Optionally, in an embodiment of the present disclosure, the preset connection condition is that the absolute value of the slope of the connection line of the sample point and the search point is maximum, and the Thiessen polygon corresponding to the sample point is adjacent to the Thiessen polygon corresponding to the search point.

[0119] Optionally, in an embodiment of the present disclosure, the preset starting condition is that there is no sample point satisfying the preset connection condition in the sample points in the same printing layer, and there is a sample point not searched in the current printing layer, then in all remaining sample points, find the point with the maximum value of (y-k·x) of the coordinates as the starting search point of the new round of connection, wherein k is the slope.

[0120] It should be noted that the foregoing explanation and description of the embodiment of the method for 3D printing in cooperation with double devices also applies to the 3D printing system in cooperation with double devices of this embodiment, which will not be described here.

[0121] The 3D printing system in cooperation with double devices according to the embodiments of the present disclosure generates sample points by the method of equidividing the geometric boundary of an irregular structure, generates Thiessen polygons by using the sample points, sorts and concatenates the Thiessen polygons inside the irregular structure, and generates a printing path suitable for 3D printing in cooperation with double devices. The printing device can perform a return motion only once in each printing layer, minimizes the collision probability in the process of cooperative printing of the device, makes large-scale concrete structures with holes printable, and improves the application scenarios and intelligent level of the 3D printing concrete technology.

[0122] In the description of the disclosure, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the disclosure. In the description of the disclosure, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or N embodiments or examples. In addition, the skilled person in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0123] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the disclosure, the meaning of "N" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0124] Any process or method descriptions in flow charts or otherwise described herein represent embodiments that can be understood as a set of steps, operations or stages of implementing custom logic functions or processes that are to be performed by a computer or computer system, and the scope of preferred embodiments of the disclosure includes additional implementation involving the performance of one or more steps, operations or stages in different order, including simultaneously, in reverse order or with additional steps, operations or stages, including in a different order, that can be understood as a set of steps, operations or stages of implementing custom logic functions or processes that are to be performed by a computer or computer system, and the scope of preferred embodiments of the disclosure includes additional implementation involving the performance of one or more steps, operations or stages in different order, including simultaneously, in reverse order or with additional steps, operations or stages, including in a different order, that can be understood as a set of steps, operations or stages of implementing custom logic functions or processes that are to be performed by a computer or computer system, and the scope of preferred embodiments of the disclosure includes additional implementation involving the performance of one or more steps, operations or stages in different order, including simultaneously, in reverse order or with additional steps, operations or stages, including in a different order, that can be understood as a set of steps, operations or stages of implementing custom logic functions or processes that are to be performed by a computer or computer system, and the scope of preferred embodiments of the disclosure includes additional implementation involving the performance of one or more steps, operations or stages in different order, including simultaneously, in reverse order or with additional steps, operations or stages, including in a different order, that can be understood as a set of steps, operations or stages of implementing custom logic functions or processes that are to be performed by a computer or computer system, and the scope of preferred embodiments of the disclosure includes additional implementation involving the performance of one or more steps, operations or stages in different order, including simultaneously, in reverse order or with additional steps, operations or stages, including in a different order, that can be understood as a set of steps, operations or stages of implementing custom logic functions or processes that are to be performed by a computer or computer system, and the scope of preferred embodiments of the disclosure includes additional implementation involving the performance of one or more steps, operations or stages in different order, including simultaneously, in reverse order or with additional steps, operations or stages, including in a different order, that can be understood as a set of steps, operations or stages of implementing custom logic functions or processes that are to be performed by a computer or computer system, and the scope of preferred embodiments of the disclosure includes additional implementation involving the performance of one or more steps, operations or stages in different order, including simultaneously, in reverse order or with additional steps, operations or stages, including in a different order, that can be understood as a set of steps,

Claims

1. A dual-device collaborative 3D printing method, wherein, The method comprises the following steps: generating a 3D printing model of a structure to be printed, separating and slicing the 3D printing model to obtain first graphic boundary lines for printing by a first mechanical arm and second graphic boundary lines for printing by a second mechanical arm; extracting boundary line segments at intersection positions of the first graphic boundary lines and the second graphic boundary lines, converting the boundary line segments into polygons, and alternately distributing the two polygons to the first mechanical arm and the second mechanical arm in the order of printing layers after dividing the polygons into two polygons, to form mortise and tenon polygons; dividing the first graphic boundary lines and the second graphic boundary lines into m sample points, generating m Thiessen polygons associated with the m sample points, sorting the m sample points, and sequentially connecting the Thiessen polygons corresponding to the sample points and the assigned mortise and tenon polygons in the manner of median lines according to the sorting results; offsetting the Thiessen polygons and the mortise and tenon polygons after the connection by one-half of the printing line width to obtain the printing paths of the first mechanical arm and the second mechanical arm.

2. The method of claim 1, wherein, The method of separating and slicing the 3D printing model to obtain first graphic boundary lines for printing by a first mechanical arm and second graphic boundary lines for printing by a second mechanical arm comprises: separating the 3D printing model to obtain a first model for printing by a first mechanical arm and a second model for printing by a second mechanical arm, and slicing the first model and the second model to obtain first graphic boundary lines of the first model and second graphic boundary lines of the second model.

3. The method of claim 1, wherein, The method of dividing the first graphic boundary lines and the second graphic boundary lines into m sample points, generating m Thiessen polygons associated with the m sample points, sorting the m sample points, and sequentially connecting the Thiessen polygons corresponding to the sample points and the assigned mortise and tenon polygons in the manner of median lines according to the sorting results comprises the following steps: unifying the starting point positions of the first graphic boundary lines and the second graphic boundary lines, dividing the first graphic boundary lines and the second graphic boundary lines into m segments, generating m sample points, generating Thiessen polygons within the boundary lines by using the m sample points, and numbering the Thiessen polygons, wherein the number of a Thiessen polygon is consistent with the number of the sample point from which the Thiessen polygon is generated; for all printing layers, selecting an arbitrary sample point with the same number as a starting search point, searching in the ±45° range in the negative direction of the Y axis from the starting search point to find a sample point satisfying a preset connection condition, and connecting the starting search point and the sample point satisfying the preset connection condition after each search; continuing the search by taking the sample point satisfying the preset connection condition as a new search point until there is no sample point satisfying the preset connection condition, and merging all the lines generated in the search process into a continuous multi-segment line; finding a sample point satisfying a preset starting condition among the sample points that have not been searched in the same printing layer as a starting search point for a new round of line generation, starting a new round of search from the starting search point in the negative direction of the Y axis to find a sample point satisfying the preset connection condition, and generating the continuous multi-segment line; repeating the search process multiple times until all sample points in the current printing layer have been searched and no new continuous multi-segment line can be generated; and repeating the search process multiple times until all sample points in the current printing layer have been searched and no new continuous multi-segment line can be generated. Connecting all the vertices of the continuous polylines in the positive direction of the Y-axis with the nearest sample points on the adjacent continuous polylines to form all the bridging polylines between the continuous polylines; Mapping the connection relationships of the sample points on the continuous polylines and the bridging polylines to the Thiessen polygons corresponding to the sample points, and generating a perpendicular line at the intersection of the Thiessen polygons having the connection relationships; Generating the same perpendicular line at the intersection of the mortise-tenon polygon and the adjacent Thiessen polygon as in the previous step.

4. The method of claim 3, wherein, The preset connection condition is that the absolute value of the slope of the line connecting the sample point and the search point is maximum, and the Thiessen polygon corresponding to the sample point is adjacent to the Thiessen polygon corresponding to the search point.

5. The method of claim 3, wherein, The preset starting condition is that there is no sample point satisfying the preset connection condition in the sample points in the same printing layer, and there is a sample point not searched in the current printing layer, then in all the remaining sample points, the point with the maximum value of (y-k·x) of the coordinates is found as the starting search point of the new round of connection, wherein k is the slope.

6. A dual-device collaborative 3D printing system, wherein, Comprise: A first mechanical arm and a second mechanical arm; A generating module configured to generate a 3D printing model of a structure to be printed, separate and slice the 3D printing model to obtain a first graphic boundary line for printing by the first mechanical arm and a second graphic boundary line for printing by the second mechanical arm; An extracting module configured to extract a boundary line segment at an intersection position of the first graphic boundary line and the second graphic boundary line, convert the boundary line segment into a polygon, and alternately allocate two polygons obtained by equally dividing the polygon to the first mechanical arm and the second mechanical arm in sequence of printing layers to form a mortise-tenon polygon; A connecting module configured to equally divide the first graphic boundary line and the second graphic boundary line into m sample points, generate m Thiessen polygons associated with the m sample points, sort the m sample points, and sequentially connect the Thiessen polygons corresponding to the sample points and the allocated mortise-tenon polygons in the form of perpendicular lines according to the sorting results; A printing module configured to offset the Thiessen polygons and the mortise-tenon polygons connected in sequence as a whole by half of the printing line width to obtain a printing path of the first mechanical arm and the second mechanical arm.

7. The system of claim 6, wherein, The generating module is further configured to separate the 3D printing model to obtain a first model for printing by the first mechanical arm and a second model for printing by the second mechanical arm, and slice the first model and the second model to obtain a first graphic boundary line of the first model and a second graphic boundary line of the second model.

8. The system of claim 6, wherein, The connecting module is specifically configured to: Unify the starting point positions of the first graphic boundary line and the second graphic boundary line, equally divide the first graphic boundary line and the second graphic boundary line into m segments, generate m sample points, generate Thiessen polygons in the boundary line by using the m sample points, and number the Thiessen polygons, wherein the number of the Thiessen polygon is consistent with the number of the sample point generating the Thiessen polygon; For all printing layers, select an arbitrary numbered same sample point as the starting search point, and search in the ±45° range in the negative direction of the Y axis of the starting search point to find a sample point that meets the preset connection condition, and after each search, connect the starting search point with the sample point that meets the preset connection condition; Continue searching with the sample point that meets the preset connection condition as the new search point until there is no sample point that meets the preset connection condition, and combine all the lines generated during the search process into a continuous multi-segment line; Find a sample point that meets the preset starting condition among the unsearched sample points in the same printing layer as the starting search point for a new round of connection, and start a new round of search from the starting search point in the negative direction of the Y axis to find a sample point that meets the preset connection condition and generate the continuous multi-segment line; Repeat the search process several times until all sample points in the current printing layer have been searched and no new continuous multi-segment line can be generated; Connect the vertex of all continuous multi-segment lines in the positive direction of the Y axis with the nearest sample point on the adjacent continuous multi-segment line to form all the bridging multi-segment lines between the continuous multi-segment lines; Map the connection relationship of all sample points on the continuous multi-segment line and the bridging multi-segment line to the Thiessen polygons corresponding to the sample points, and generate a perpendicular line at the intersection of the Thiessen polygons with the connection relationship; Generate the same perpendicular line as the previous step at the intersection of the mortise-tenon polygon and its adjacent Thiessen polygon.

9. The system of claim 8, wherein, The preset connection condition is that the absolute value of the slope of the line connecting the sample point and the search point is maximum, and the Thiessen polygon corresponding to the sample point is adjacent to the Thiessen polygon corresponding to the search point.

10. The system of claim 8, wherein, The preset starting condition is that there is no sample point that meets the preset connection condition among the sample points in the same printing layer, and there is an unsearched sample point in the current printing layer, then among all the remaining sample points, find the point with the maximum (y-k·x) value of the coordinates as the starting search point for a new round of connection, where k is the slope.

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