Solid object fabrication system, control device, program, and solid object fabrication method

Abstract

[Problem] To realize a technique with which it is possible to appropriately determine the internal structure of a three-dimensional object. [Solution] This solid object fabrication system 1 comprises a head 21, an articulated robot 22, a structure determination unit 153, a route generation unit 154, a head movement control unit 155, and a discharge control unit 156. The head 21 discharges a fabrication material for fabricating a solid object. The articulated robot 22 moves the head 21. The structure determination unit 153 determines the structure of the solid object, which includes an internal structure, on the basis of three-dimensional data pertaining to the solid object. The route generation unit 154 sets, on the basis of the structure determined by the structure determination unit 153, a tool path over which one built-up layer of the solid object including the internal structure is produced in an unbroken action. The head movement control unit 155 and the discharge control unit 156 move the head 21 by using the articulated robot 22 and cause the head 21 to discharge the fabrication material in accordance with the tool path generated by the route generation unit 154.

Description

Three-dimensional object modeling system, control device, program, and three-dimensional object modeling method

[0001] The present invention relates to a three-dimensional object modeling system, a control device, a program, and a three-dimensional object modeling method.

[0002] In recent years, technologies for modeling large three-dimensional objects such as building members and buildings using three-dimensional object modeling devices such as 3D printers have been increasingly used. For example, Non-Patent Document 1 describes forming a formwork for a shell structure in architecture by 3D printing.

[0003] “Design and Fabrication of Formwork for Shell Structures Based on 3D-printing Technology”, Xiao Zhang et al., 39th eCAADe, Performance based design - Volume 1 pp. 487 - 496

[0004] However, in conventional technologies for modeling three-dimensional objects, a method for determining an internal structure suitable for modeling large three-dimensional objects such as building members and buildings has not been established, and it has been difficult to appropriately determine an internal structure according to the structure of the three-dimensional object.

[0005] An object of the present invention is to realize a technology capable of appropriately determining the internal structure of a three-dimensional object.

[0006] To achieve the above object, a three-dimensional object modeling system according to an aspect of the present invention includes: discharging means for discharging a modeling material for modeling a three-dimensional object; moving means for moving the discharging means; structure determination means for determining the structure of the three-dimensional object including an internal structure based on the three-dimensional data of the three-dimensional object; path generation means for setting a tool path for continuously writing a single layer surface of the three-dimensional object including the internal structure based on the structure determined by the structure determination means; and control means for moving the discharging means by the moving means and discharging the modeling material according to the tool path generated by the path generation means.

[0007] According to the present invention, a technology capable of appropriately determining the internal structure of a three-dimensional object can be realized.

[0008] This is a schematic diagram showing the system configuration of a three-dimensional object modeling system 1 according to one embodiment of the present invention. This is a block diagram showing the hardware configuration of an information processing device 800 that constitutes the control system of the three-dimensional object modeling system 1. This is a block diagram showing the functional configuration of the control unit 10. This is a schematic diagram showing a method for determining the internal structure in the first embodiment. This is a schematic diagram showing a state in which a group of reference points is set within a closed figure in slice data. This is a schematic diagram showing an example of the internal structure of a three-dimensional object. This is a schematic diagram showing a state in which a Voronoi diagram is created based on a group of reference points. This is a schematic diagram showing a state in which an offset is set on each edge constituting a cell in a Voronoi diagram. This is a schematic diagram showing a state in which a cell (polygon) has double edges formed by the offset. This is a schematic diagram showing a state in which a minimum spanning tree that passes through all cells is set. This is a schematic diagram showing a state in which the edges that the minimum spanning tree passes through are cut. This is a schematic diagram showing an example of a process in which an open edge is connected to an edge of an adjacent cell. This is a schematic diagram showing a state in which an open edge is connected to an edge of an adjacent cell in a synaptic connection configuration. This is a schematic diagram showing a cross-type connection configuration where an open edge is connected to the edge of an adjacent cell. This is a flowchart showing the flow of the control data generation process performed by the 3D object fabrication system 1. This is a flowchart showing the flow of the 3D object fabrication process performed by the 3D object fabrication system 1. This is a schematic diagram showing an example of a 3D object fabricated by the 3D object fabrication system 1 (an example of fabrication in the cross type). This is a schematic diagram showing another example of a 3D object fabricated by the 3D object fabrication system 1 (an example of fabrication in the synapse type). This is a schematic diagram showing an example of creating gaps in the internal structure by shortcutting the vertices of the polygons that make up the cell.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. [First Embodiment] [System Configuration] The three-dimensional object manufacturing system 1 according to this embodiment is realized as one form of a three-dimensional object manufacturing system to which the present invention is applied, and is configured as a 3D printer capable of manufacturing large three-dimensional objects such as building components and structures. In the three-dimensional object manufacturing system 1, the internal structure (infill) is determined according to the structure of the three-dimensional object to be manufactured, and a toolpath (head movement path) is generated that draws the structure of the three-dimensional object, including the internal structure, in a predetermined form in a single stroke, and the three-dimensional object is manufactured using a path without travel. Therefore, an appropriate internal structure can be made according to the three-dimensional object to be manufactured, and by moving the head along the path generated in this way, large three-dimensional objects can be manufactured efficiently, and a deterioration in quality due to unnecessary stringing of material can be suppressed. Accordingly, the three-dimensional object manufacturing system 1 to which the present invention is applied can realize a technology that can appropriately determine the internal structure of a three-dimensional object.

[0010] Figure 1 is a schematic diagram showing the system configuration of a three-dimensional object manufacturing system 1 according to one embodiment of the present invention. As shown in Figure 1, the three-dimensional object manufacturing system 1 comprises a control unit 10 and a manufacturing unit 20, and the control unit 10 and the manufacturing unit 20 are configured to communicate with each other by wired communication via a cable or the like, or by wireless communication via a wireless LAN (Local Area Network) or the like.

[0011] The control unit 10 is composed of an information processing device such as a PC (Personal Computer). The control unit 10 stores the 3D data of the object to be fabricated and generates toolpath data representing the movement path of the head 21 in the fabrication unit 20 from the 3D data of the object. For example, the control unit 10 converts the 3D data of the object to be fabricated (3D CAD data or 3D CG data, etc.) into STL (Stereo Lithography) data and generates slice data by slicing it to a predetermined thickness. Then, the control unit 10 determines the internal structure in the slice data of each layer using a method described later and generates toolpath data for fabricating the layers of the object including the internal structure. The control unit 10 generates toolpath data for all layers of the object to be fabricated and generates control data for controlling the fabrication unit 20 based on the toolpath data. At this time, the control unit 10 accepts the setting of various parameters that should be specified in the fabrication of the object, such as the width of the path that constitutes the internal structure.

[0012] Furthermore, the control unit 10 operates the molding unit 20 according to control data, causing the head to move according to the toolpath and eject the molding material from the head 21. The molding unit 20 comprises a head 21 for ejecting the molding material and a multi-joint robot 22 for moving the head 21 in three dimensions.

[0013] The head 21 includes a material container 21a for accumulating the supplied molding material and a nozzle 21b for discharging the molding material. The molding material can be sequentially supplied to the material container 21a via a tube or the like. The nozzle 21b has a predetermined diameter selected according to the three-dimensional object to be molded, and controls the discharging of the molding material by opening and closing the supply path of the molding material accumulated in the material container 21a. In this embodiment, the nozzle 21b has a nozzle diameter of 4 to 5 mm. For example, if the nozzle diameter is 4 mm, the discharging material is layered with a width of about 5 mm. As a result of drawing two adjacent toolpaths in a single stroke, the width (thickness) of the layered molding material becomes about 10 mm.

[0014] Furthermore, in this embodiment, the molding material extruded from the head 21 is made of a resin, cement, mortar, or concrete that can constitute building components or structures, and hardens after being layered to exhibit a predetermined strength. As an example, the molding material extruded from the head 21 can be a resin made from recycled plastic.

[0015] The articulated robot 22 is, for example, a 6-axis or 8-axis vertical articulated robot, and moves the head 21 to any position and orientation in three dimensions according to the control data transmitted from the control unit 10. In the process of creating a three-dimensional object, the articulated robot 22 moves the head 21 in three dimensions while maintaining the nozzle 21b of the head 21 facing vertically downward. The articulated robot 22 may be other types of transport devices, such as a horizontal articulated robot, as long as it is capable of moving the head 21 in three dimensions.

[0016] [Hardware Configuration of the Control System] Next, the hardware configuration of the control system of the 3D modeling system 1 will be described. Figure 2 is a block diagram showing the hardware configuration of the information processing device 800 that constitutes the control system of the 3D modeling system 1. The information processing device 800 constitutes the control unit 10 and is configured by an information processing device such as a PC. Note that the information processing device 800 can also be configured by an information processing device such as a server computer, smartphone, or tablet terminal, as long as it is capable of performing information processing in the 3D modeling system 1.

[0017] As shown in Figure 2, the information processing device 800 includes a CPU (Central Processing Unit) 811, a ROM (Read Only Memory) 812, a RAM (Random Access Memory) 813, a bus 814, an input unit 815, an output unit 816, a storage unit 817, a communication unit 818, and a drive 819.

[0018] The CPU 811 executes various processes according to the program recorded in the ROM 812 or the program loaded into the RAM 813 from the storage unit 817. The RAM 813 also stores data and other information necessary for the CPU 811 to execute various processes.

[0019] The CPU 811, ROM 812, and RAM 813 are interconnected via a bus 814. An input unit 815, an output unit 816, a storage unit 817, a communication unit 818, and a drive 819 are connected to the bus 814.

[0020] The input unit 815 consists of various buttons and other components, and inputs various information according to the instructions. The output unit 816 consists of a display, speaker, etc., and outputs video and audio. If the information processing device 800 is configured as a smartphone or tablet terminal, the input unit 815 and the display of the output unit 816 may be placed on top of each other to form a touch panel. The storage unit 817 consists of a hard disk or DRAM (Dynamic Random Access Memory), etc., and stores various data used in the 3D object modeling system 1. The communication unit 818 controls communication with other devices via a network.

[0021] A removable media 831, consisting of a magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, is appropriately mounted on the drive 819. The program read from the removable media 831 by the drive 819 is installed in the storage unit 817 as needed. In addition to the above configuration, the information processing device 800 may be appropriately equipped with additional configurations such as a GPU (Graphics Processing Unit) and ports that support various standards.

[0022] [Functional Configuration] Next, the functional configuration of the three-dimensional object manufacturing system 1 will be described. Figure 3 is a block diagram showing the functional configuration of the control unit 10. As shown in Figure 3, the control unit 10 includes, as functions of the CPU 811, a design data acquisition unit 151, a slice data acquisition unit 152, a structure determination unit 153, a path generation unit 154, a head movement control unit 155, an ejection control unit 156, and an operation history recording unit 157. The storage unit 817 also includes a design data storage unit 171, a manufacturing data storage unit 172, and an operation history storage unit 173.

[0023] The design data storage unit 171 stores the three-dimensional data (3D CAD data or 3D CG data, etc.) of the three-dimensional object to be fabricated in the three-dimensional object fabrication system 1. The fabrication data storage unit 172 stores various data set or generated in the slice data acquisition unit 152, structure determination unit 153, and path generation unit 154 (various data related to the fabrication of three-dimensional objects, such as the offset values ​​set on the edges of the cells described later, toolpath data, and control data including the movement speed of the head 21). The operation history storage unit 173 stores operation history data of the three-dimensional object fabrication system 1 (position data of each joint of the articulated robot 22 or data of the fabrication material discharge history at the head 21, etc.) in association with time.

[0024] The design data acquisition unit 151 acquires three-dimensional data (design data) of the three-dimensional object to be fabricated in the three-dimensional object fabrication system 1. For example, the design data acquisition unit 151 can acquire design data from other devices via a network or by reading it from removable media such as a USB memory stick.

[0025] The slice data acquisition unit 152 converts the 3D data (design data) of a three-dimensional object into STL data and acquires slice data for 3D printing by slicing the STL data at a pitch of a set thickness. In this embodiment, the slice data generated by the slice data acquisition unit 152 represents the shape obtained by slicing the structure shown in the design data, and does not include the internal structure.

[0026] The structure determination unit 153 determines the internal structure, including the infill, in the slice data of each layer acquired by the slice data acquisition unit 152. Figure 4 is a schematic diagram showing the method for determining the internal structure in this embodiment. As shown in Figure 4, when determining the internal structure for slice data, the following processes are generally performed: (1) setting of reference point cloud, (2) conversion to a Voronoi diagram, and (3) conversion to a one-pass diagram.

[0027] In "(1) Setting the reference point cloud," multiple reference points are set within the closed shape in the slice data to form cells that define the internal structure. In "(2) Converting to a Voronoi diagram," the regions are divided based on which point in the reference point cloud the points within the closed shape in the slice data are closest to the set reference points, and each divided region is set as a cell that defines the internal structure. In "(3) Converting to a one-pass," each side of the set cells is converted into a one-pass that can be drawn in a single stroke, and the toolpath is set.

[0028] Specifically, the following processes are performed in each step of Figure 4. (1) Setting of reference point group Figure 5 is a schematic diagram showing the state in which a reference point group is set within a closed figure in slice data. As shown in Figure 5, the density of the reference points to be set is set according to the strength required for the part of the three-dimensional object that the closed figure in slice data constitutes, and the required lightness and other attributes. The density of the reference points to be set can be set by the operator, who sets these strength or lightness and other attributes, and the structure determination unit 153 can set it automatically according to the set values. However, the operator may set the density of the reference points, and the structure determination unit 153 may automatically set the reference points according to the set density.

[0029] Furthermore, in this embodiment, the group of reference points set as initial values ​​by the structure determination unit 153 is displayed on the output unit 816's display, and the operator can manually delete unnecessary reference points or manually add reference points via the input unit 815. For example, the operator can identify the positions where structural elements such as screws will be placed from the completed drawing of the three-dimensional object and set the system so that reference points are not distributed at these positions. By setting reference points in this way, it is possible to make the strength differ depending on the part of the three-dimensional object, or to configure the system so that internal structures are not placed in specific parts of the three-dimensional object.

[0030] Figure 6 is a schematic diagram showing an example of the internal structure of a three-dimensional object. As shown in Figure 6, it is possible to increase the strength by arranging the internal structure more densely in areas where greater stress is applied, or to omit the internal structure in areas where components such as screws will be installed later. In this embodiment, such a structure can be realized by adjusting the arrangement of the reference point group.

[0031] (2) Conversion to Voronoi Diagram Figure 7 is a schematic diagram showing the state in which a Voronoi diagram is created based on a set of reference points. As shown in Figure 7, in the creation of a Voronoi diagram, the distance of each point in a closed figure in the slice data is calculated relative to the set reference points, and each point in the closed figure in the slice data is assigned to the region corresponding to the nearest reference point. As a result, the closed figure in the slice data is divided into multiple regions. Each of these divided regions is set as a cell that defines the internal structure.

[0032] (3) Conversion to a single pass In the conversion to a single pass (single-stroke path), first, an offset is set on each edge that makes up the cell in the Voronoi diagram. Figure 8 is a schematic diagram showing the state in which an offset is set on each edge that makes up the cell in the Voronoi diagram. In Figure 8, an offset corresponding to the diameter of the nozzle 21b (extrusion width of the molding material) is set on both sides of each edge of the cell in the Voronoi diagram. As a result, a double edge is formed at the cell boundary.

[0033] Figure 9 is a schematic diagram showing the state of a cell (polygon) where double edges are formed by an offset. In the state shown in Figure 9, each cell is separated as a result of the formation of double edges. Therefore, in order to make the internal structure composed of each cell a one-pass (single-stroke path), a process is performed to connect the edges between cells. To connect the edges between cells, first, a minimum spanning tree that passes through all cells is set up. In this embodiment, the Kruskal algorithm is used to set up a minimum spanning tree that passes through all cells.

[0034] Figure 10 is a schematic diagram showing the state in which a minimum spanning tree passing through all cells is set up. As shown in Figure 10, an arbitrary cell (reference point) is selected as the starting point, and a continuous line (minimum spanning tree) passing through all cells is set up using Kruskal's method. In Figure 10, the cell marked with a circle is selected as the starting point. At this time, weights are set for each edge that makes up a cell in the Voronoi diagram, and by selecting the edges with the smallest weights first, a continuous line passing through all cells can be set up.

[0035] Next, in order to open the edges of each cell, which is a closed polygon, the edges that the minimum spanning tree passes through are cut in each cell. Figure 11 is a schematic diagram showing the state in which the edges that the minimum spanning tree passes through are cut. As shown in Figure 11, the edges that the minimum spanning tree passes through are cut in each cell, and the closed polygon is opened.

[0036] Next, the opened edge is connected to the edge of an adjacent cell. Figure 12 is a schematic diagram showing an example of the process of connecting an opened edge to the edge of an adjacent cell. As shown in Figure 12, when connecting an opened edge to the edge of an adjacent cell, either a synaptic or cross-type connection can be used. Figure 13 is a schematic diagram showing the state in which an opened edge has been connected to the edge of an adjacent cell using a synaptic connection. In the synaptic connection, when the edges of adjacent cells are connected, the endpoints located on the same side with respect to the minimum spanning tree are connected at the severed edge. Therefore, in the synaptic connection, a single path (one-stroke path) is set up without overlapping paths.

[0037] Figure 14 is a schematic diagram showing a cross-type connection configuration where an open edge is connected to an edge of an adjacent cell. In a cross-type connection configuration, when edges of adjacent cells are connected, the endpoints on opposite sides of the minimum spanning tree are connected at the cut edge. Therefore, in a cross-type connection configuration, a path intersection is formed at the edges traversed by the minimum spanning tree, and a one-pass (single-stroke path) is established.

[0038] Returning to the explanation of Figure 3, the path generation unit 154 generates toolpath data for moving the head 21 to create a three-dimensional object. At this time, the path generation unit 154 generates toolpath data for the movement path of the head 21 for each slice plane, including the internal structure determined by the structure determination unit 153. However, if similar slice planes are stacked, it is possible to set the toolpath for one slice plane using the above method and then set the same toolpath for other similar slice planes to perform the manufacturing. The path generation unit 154 also stores the generated toolpath data in the manufacturing data storage unit 172 as part of the control data.

[0039] The head movement control unit 155 controls the articulated robot 22 of the molding unit 20 according to the control data stored in the molding data storage unit 172, moving the head 21 along the toolpath at a set speed. The ejection control unit 156 controls the head 21 of the molding unit 20 according to the control data stored in the molding data storage unit 172, ejecting the molding material from the nozzle 21b.

[0040] The operation history recording unit 157 stores operation history data of the three-dimensional object modeling system 1 (such as position data of each joint of the articulated robot 22 or data on the ejection history of the modeling material in the head 21) in association with time.

[0041] [Operation] Next, the operation of the three-dimensional object modeling system 1 will be described. [Control Data Generation Process] FIG. 15 is a flowchart showing the flow of the control data generation process executed by the three-dimensional object modeling system 1. The control data generation process starts in response to an operation instructing the execution of the control data generation process via the input unit 815 of the control unit 10.

[0042] When the control data generation process is started, in step S1, the design data acquisition unit 151 acquires three-dimensional data (design data) of the three-dimensional object to be modeled. In step S2, the slice data acquisition unit 152 converts the three-dimensional data (design data) of the three-dimensional object into STL data and slices it at a pitch of the set thickness, thereby acquiring slice data for 3D printing.

[0043] In step S3, the structure determination unit 153 determines an internal structure including infill in the slice data of each layer acquired by the slice data acquisition unit 152. In step S4, the path generation unit 154 generates data of a path (tool path) for moving the head 21 to model the three-dimensional object. In step S5, the path generation unit 154 stores the generated tool path data in the modeling data storage unit 172 as part of the control data.

[0044] In step S6, the path generation unit 154 determines whether the generation of the control data has ended (whether all the control data of the three-dimensional object to be modeled has been generated). If the generation of the control data has not ended, it is determined as NO in step S6, and the process proceeds to step S2. On the other hand, if the generation of the control data has ended, it is determined as YES in step S6, and the control data generation process ends.

[0045] [Three-Dimensional Object Modeling Process] FIG. 16 is a flowchart showing the flow of the three-dimensional object modeling process executed by the three-dimensional object modeling system 1. The three-dimensional object modeling process starts in response to an operation instructing the execution of the three-dimensional object modeling process via the input unit 815 of the control unit 10.

[0046] When the three-dimensional object shaping process starts, in step S11, the head movement control unit 155 acquires the control data stored in the shaping data storage unit 172. In step S12, the ejection control unit 156 moves the head 21 of the shaping unit 20 and ejects the shaping material from the nozzle 21b according to the control data stored in the shaping data storage unit 172.

[0047] In step S13, the head movement control unit 155 determines whether the shaping of the three-dimensional object is completed. If the shaping of the three-dimensional object is not completed, it is determined as NO in step S13, and the process proceeds to step S12. On the other hand, if the shaping of the three-dimensional object is completed, it is determined as YES in step S13, and the process proceeds to step S14. In step S14, the operation history recording unit 157 records the operation history. After step S14, the three-dimensional object shaping process ends.

[0048] As described above, the three-dimensional object shaping system 1 according to the present embodiment determines the internal structure (infill) according to the structure of the three-dimensional object to be shaped, and generates data of a tool path (the movement path of the head 21) that draws the structure of the three-dimensional object including the internal structure at one stroke. At this time, the three-dimensional object shaping system 1 divides the closed figure in the slice data into regions (cells) in the Voronoi diagram, and connects the sides of adjacent cells in a cross-type or synaptic-type connection form, thereby generating a tool path for shaping in one pass (one-stroke path). [[ID=八]]

[0049] Therefore, an appropriate internal structure can be set according to the three-dimensional object to be shaped. By moving the head 21 along the path generated in this way, a large three-dimensional object can be efficiently shaped by a non-traveling path, and a decrease in quality due to stringing of unnecessary materials can be suppressed. Therefore, according to the three-dimensional object shaping system 1 to which the present invention is applied, a technique capable of appropriately determining the internal structure of a three-dimensional object can be realized.

[0050] In particular, when creating large three-dimensional objects, the nozzle diameter tends to be larger, so even if the material discharge is stopped, the material does not immediately stop falling, which can cause stringing. To completely prevent this, it is not easy to avoid stringing, as it takes time for the material to stop falling. In contrast, in the three-dimensional object creation system 1 to which the present invention is applied, the toolpath is generated in a single pass (single-stroke path), so there is no travel, and the occurrence of unnecessary material stringing can be prevented.

[0051] [Example 1] Figure 17 is a schematic diagram showing an example of a three-dimensional object created by the three-dimensional object creation system 1 (an example of creation using a cross-type connection). In Figure 17, a formwork for a building (a concrete molding formwork with a height of approximately 70 cm) is created as a three-dimensional object, and an example is shown in which the internal structure is created on the outer shell of the three-dimensional object using a cross-type connection configuration. As shown in Figure 17, by connecting adjacent cells using a cross-type connection configuration, the toolpath includes intersections, resulting in a high strength for the internal structure.

[0052] [Example 2] Figure 18 is a schematic diagram showing another example of a three-dimensional object fabricated by the three-dimensional object fabrication system 1 (an example of fabrication using a synapse type). In Figure 18, a formwork for a building (a concrete molding formwork with a height of approximately 70 cm) is fabricated as a three-dimensional object, and an example is shown in which the internal structure is fabricated to the outer shell of the three-dimensional object using a synapse-type connection configuration. As shown in Figure 18, by connecting adjacent cells using a synapse-type connection configuration, the layered surface of the internal structure can be made flat. Furthermore, compared to the case of a cross-type connection configuration, the load applied to the layered fabricated material becomes more uniform, making it possible to select softer fabricated materials, thus broadening the range of fabricated material choices, and improving the molding accuracy of the connection parts with adjacent cells.

[0053] [Modification 1] In the above embodiment, when determining the internal structure for slice data, the density of reference points is set according to the strength required for the part of the three-dimensional object that is formed by the closed figure in the slice data, and the required lightness and other attributes. In contrast, when determining the internal structure for slice data, the structural determination unit 153 may perform a structural analysis of the three-dimensional object to be fabricated, and according to the results of the structural analysis, it may automatically adjust the density of reference points so that reference points are distributed more densely in parts that require strength and less densely in parts that require lightness. This makes it possible to easily determine an appropriate internal structure according to the attributes required for the three-dimensional object. Alternatively, the structural determination unit 153 may automatically identify the positions where structures such as screws will be placed based on the completed drawing of the three-dimensional object, and no reference points may be set at these positions. This can prevent the formation of internal structures in inappropriate locations and reduce the effort required for the operator to adjust the internal structure.

[0054] [Modification 2] In the above embodiment, after creating a Voronoi diagram for a closed figure in slice data, it is possible to adjust the size of the gap formed between adjacent cells at the corners of the polygons constituting the cells. For example, by dividing the sides of the polygon constituting the cell into three, shortcutting the vertices sandwiched between adjacent sides, and forming sides that connect the ends of the central parts of adjacent sides, the internal structure of the vertex portion of the polygon can be replaced with a gap. Figure 19 is a schematic diagram showing an example of forming a gap in the internal structure by shortcutting the vertices of the polygon constituting the cell. In Figure 19, the points on the sides of each cell indicate the points that divide the side into three equal parts. As shown in Figure 19(a), after setting cells within a closed figure in slice data using the method shown in the above embodiment, as shown in Figure 19(b), a gap can be formed at the vertex portion (corner) of the vertex to be shortcutted by connecting the ends of the central parts of the sides that sandwich the vertex to be shortcutted. Then, by converting the cell in the state shown in Figure 19(b) to a one-pass toolpath, each side of multiple cells can be converted into a toolpath that can be drawn in a single stroke. In Figure 19, an example is shown where one vertex in a cell is targeted for shortcutting, but it is also possible to target multiple other vertices in a cell for shortcutting. This makes it possible to change the ratio of parts formed as double toolpaths to parts formed as single toolpaths while utilizing the cells generated by converting to a Voronoi diagram, thereby enabling the reduction of the size of the printed object.

[0055] [Modification 3] In the above embodiment, a combination of synaptic and cross-type connection configurations may be used to connect adjacent cells. As described above, the synaptic connection configuration has the advantage of allowing the layered surface of the internal structure to be flat. In addition, compared to the cross-type connection configuration, the load applied to the layered molding material becomes more uniform, making it possible to select softer molding materials, thus broadening the range of molding material choices, and improving the molding accuracy of the connection parts with adjacent cells. On the other hand, the cross-type connection configuration has the advantage of having high internal structure strength because the toolpath includes intersections. Therefore, by combining synaptic and cross-type connection configurations according to the attributes required for each part of the three-dimensional object to be molded, it becomes possible to mold a three-dimensional object with a more appropriate internal structure.

[0056] As described above, the three-dimensional object manufacturing system 1 according to this embodiment includes a head 21, an articulated robot 22, a structure determination unit 153, a path generation unit 154, a head movement control unit 155, and an ejection control unit 156. The head 21 ejects a manufacturing material for creating a three-dimensional object. The articulated robot 22 moves the head 21. The structure determination unit 153 determines the structure of the three-dimensional object, including its internal structure, based on the three-dimensional data of the object. The path generation unit 154 sets a toolpath that draws one layer of the three-dimensional object, including its internal structure, in a single stroke, based on the structure determined by the structure determination unit 153. The head movement control unit 155 and the ejection control unit 156 move the head 21 using the articulated robot 22 and eject the manufacturing material according to the toolpath generated by the path generation unit 154. This allows for the creation of an appropriate internal structure for the three-dimensional object being fabricated. By moving the head 21 along this generated path, large three-dimensional objects can be efficiently fabricated using a travel-free path, while suppressing quality degradation due to unnecessary material stringing, etc. Therefore, a technology that can appropriately determine the internal structure of a three-dimensional object can be realized.

[0057] The structure determination unit 153 determines the internal structure by dividing closed shapes in the slice data of the three-dimensional data of the three-dimensional object and generating multiple cells. This makes it possible to easily generate an appropriate internal structure according to the three-dimensional object being fabricated.

[0058] The structure determination unit 153 generates multiple cells in the slice data of the three-dimensional data of the three-dimensional object by generating a Voronoi diagram based on a set of reference points set within a closed figure, and determines the internal structure. This makes it possible to appropriately divide the interior of the three-dimensional object into multiple cells in the slice data of the three-dimensional data of the object.

[0059] The structural determination unit 153 adds or deletes reference point groups related to the generation of a Voronoi diagram for a portion of a closed figure in the slice data of the three-dimensional data of the three-dimensional object. This makes it possible to adjust the internal structure according to the attributes such as the required strength and lightweight of the portion of the three-dimensional object that is composed of the closed figure in the slice data.

[0060] The structure determination unit 153 sets an offset on the edge of the cell that corresponds to the extrusion width of the molding material by the head 21. This makes it possible to create a double structure that allows the cell boundary to be drawn in a single stroke, and to determine an internal structure that is suitable for the extrusion width of the molding material by the head 21.

[0061] The structure determination unit 153 connects the edges of adjacent cells in a predetermined connection configuration and sets the edges of the connected cells as a toolpath that can be drawn in a single continuous stroke. This makes it possible to set a toolpath that can draw the entire set of cells that make up the internal structure of a three-dimensional object in a single continuous stroke.

[0062] The structural determination unit 153 connects the edges of adjacent cells in a synaptic connection configuration where the toolpaths do not intersect. This allows for the connection of adjacent cell edges in a configuration where the layered surface of the internal structure has a flat shape. Furthermore, because the load applied to the layered material is evenly distributed, it becomes possible to select softer materials, thus broadening the range of materials that can be used. In addition, the molding accuracy of the connection parts between adjacent cells can be improved.

[0063] The structural determination unit 153 connects the edges of adjacent cells in a cross-shaped connection configuration where toolpaths intersect. This allows for the connection of adjacent cell edges in a connection configuration that provides high internal structural strength.

[0064] The structure determination unit 153 sets reference points at different densities for each part of the slice data of the three-dimensional data of the three-dimensional object. This makes it possible to increase strength by arranging the internal structure at a higher density, or to omit the internal structure from certain parts.

[0065] The structural determination unit 153 performs a structural analysis of the three-dimensional object to be fabricated and determines the internal structure based on the results of the structural analysis. This makes it possible to easily determine an appropriate internal structure according to the attributes required for the three-dimensional object.

[0066] This process involves creating large three-dimensional objects, including building components or structures. This allows for the appropriate determination of the internal structure of objects subjected to greater loads, enabling more efficient object creation.

[0067] Furthermore, the present invention can be modified, improved, etc. as appropriate within the scope of achieving the effects of the present invention, and is not limited to the embodiments described above. For example, in the embodiments described above, the head 21 can be configured in various ways, such as fused deposition modeling or other methods, as long as it is capable of creating large three-dimensional objects. Also, in the embodiments described above, examples were given of using resin, cement, mortar, or concrete as the molding material, but any material capable of creating large three-dimensional objects can be used, such as metallic materials.

[0068] Furthermore, the present invention can be implemented by appropriately combining the above embodiments and their variations. The processing in the above embodiments can be performed by either hardware or software. That is, the three-dimensional object modeling system 1 only needs to be equipped with a function that can perform the above processing, and the functional configuration and hardware configuration to realize this function are not limited to the examples above. When the above processing is performed by software, the program constituting that software is installed on the computer from a network or storage medium.

[0069] The storage medium for storing the program consists of removable media distributed separately from the main unit of the device, or storage media pre-installed in the main unit of the device. Removable media consists of, for example, magnetic disks, optical disks, or magneto-optical disks. Optical disks consist of, for example, CD-ROM (Compact Disk-Read Only Memory), DVD (Digital Versatile Disk), Blu-ray Disc (registered trademark), etc. Magneto-optical disks consist of, for example, MD (Mini-Disk). Furthermore, storage media pre-installed in the main unit of the device consists of, for example, ROM or hard disks on which the program is stored.

[0070] 1. Three-dimensional object modeling system, 10. Control unit, 20. Modeling unit, 21. Head, 21a. Material container, 21b. Nozzle, 22. Articulated robot, 151. Design data acquisition unit, 152. Slice data acquisition unit, 153. Structure determination unit, 154. Path generation unit, 155. Head movement control unit, 156. Discharge control unit, 157. Operation history recording unit, 171. Design data storage unit, 172. Modeling data storage unit, 173. Operation history storage unit, 800. Information processing device, 811. CPU, 812. ROM, 813. RAM, 814. Bus, 815. Input unit, 816. Output unit, 817. Storage unit, 818. Communication unit, 819. Drive, 831. Removable media

Claims

1. A three-dimensional object manufacturing system comprising: an ejection means for ejecting a molding material for forming a three-dimensional object; a moving means for moving the ejection means; a structure determination means for determining the structure of the three-dimensional object, including its internal structure, based on three-dimensional data of the object; a path generation means for setting a toolpath to draw one layer of the three-dimensional object, including its internal structure, in a single stroke, based on the structure determined by the structure determination means; and a control means for moving the ejection means by the moving means and ejecting the molding material according to the toolpath generated by the path generation means.

2. The three-dimensional object fabrication system according to claim 1, characterized in that the structure determination means determines the internal structure by dividing a closed figure in the slice data of the three-dimensional data of the three-dimensional object to generate a plurality of cells.

3. The three-dimensional object fabrication system according to claim 1 or 2, characterized in that the structure determination means generates a plurality of cells by generating a Voronoi diagram based on a set of reference points set within a closed figure in the slice data of the three-dimensional data of the three-dimensional object, and determines the internal structure.

4. The three-dimensional object fabrication system according to claim 3, characterized in that the structure determination means adds or deletes the reference point group for generating the Voronoi diagram to a part of the closed figure in the slice data of the three-dimensional data of the three-dimensional object.

5. The three-dimensional object molding system according to claim 1 or 2, characterized in that the structure determination means sets an offset on the side of the cell corresponding to the extrusion width of the molding material by the extrusion means.

6. The three-dimensional object fabrication system according to claim 1 or 2, characterized in that the structure determination means connects the edges of adjacent cells in a predetermined connection configuration and sets the edges of the connected plurality of cells as a toolpath that draws in a single stroke.

7. The three-dimensional object fabrication system according to claim 6, characterized in that the structure determination means connects the edges of adjacent cells in a synaptic connection configuration in which the toolpaths do not intersect.

8. The three-dimensional object fabrication system according to claim 6, characterized in that the structure determination means connects the edges of adjacent cells in a cross-shaped connection configuration in which toolpaths intersect.

9. The three-dimensional object fabrication system according to claim 1 or 2, characterized in that the structure determination means sets the reference points at different densities for each part of the slice data of the three-dimensional data of the three-dimensional object.

10. The three-dimensional object fabrication system according to claim 1 or 2, characterized in that the structural determination means performs a structural analysis of the three-dimensional object to be fabricated and determines the internal structure based on the results of the structural analysis.

11. The three-dimensional object manufacturing system according to claim 1 or 2, characterized in that it manufactures a large three-dimensional object including building components or a structure as the three-dimensional object.

12. A control device for controlling a three-dimensional object manufacturing system comprising: an ejection means for ejecting a manufacturing material for manufacturing a three-dimensional object; and a moving means for moving the ejection means, the control device comprising: a structure determination means for determining the structure of the three-dimensional object, including its internal structure, based on three-dimensional data of the three-dimensional object; a path generation means for setting a toolpath for drawing one layer of the three-dimensional object, including its internal structure, in a single stroke, based on the structure determined by the structure determination means; and a control means for moving the ejection means by the moving means and ejecting the manufacturing material according to the toolpath generated by the path generation means.

13. A program comprising a computer constituting a control device for controlling a three-dimensional object manufacturing system, which includes an ejection means for ejecting a manufacturing material for creating a three-dimensional object, and a moving means for moving the ejection means, characterized in that it implements: a structure determination function that determines the structure of the three-dimensional object, including its internal structure, based on three-dimensional data of the three-dimensional object; a path generation function that sets a toolpath for drawing one layer surface of the three-dimensional object, including its internal structure, in a single stroke, based on the structure determined by the structure determination function; and a control function that moves the ejection means by the moving means and ejects the manufacturing material according to the toolpath generated by the path generation function.

14. A method for creating a three-dimensional object that a three-dimensional object creation system can perform, comprising: an ejection step of ejecting a modeling material for creating a three-dimensional object using an ejection means; a movement step of moving the ejection means; a structure determination step of determining the structure of the three-dimensional object, including its internal structure, based on three-dimensional data of the three-dimensional object; a path generation step of setting a toolpath to draw one layer of the three-dimensional object, including its internal structure, in a single stroke, based on the structure determined in the structure determination step; and a control step of controlling the movement of the ejection means in the movement step and ejecting the modeling material according to the toolpath generated in the path generation step.

Images