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Title:
APPARATUS FOR AUTOMATED ADDITIVE MANUFACTURING OF A THREE DIMENSIONAL OBJECT AND A METHOD THEREOF
Document Type and Number:
WIPO Patent Application WO/2021/054894
Kind Code:
A1
Abstract:
An apparatus for automated additive manufacturing of a three dimensional (3D) object. The apparatus including a platform having a surface; a material deposition module having a deposition head for depositing a material, the deposition head movable along a deposition path to deposit a layer of the material, the deposition path being based on a shape generated from a layer image of a CAD model of the 3D object sliced at the layer height; a sensor arrangement disposed to scan and map a surface of the deposited layer; and a subtractive machining module having a machining tool movable to machine the surface of the deposited layer based on comparing a surface roughness of the surface against a pre-set surface flatness tolerance. The material deposition module sets a subsequent layer height for deposition based on a finished height of the deposited layer. A corresponding method thereof.

Inventors:
SOH GIM SONG (SG)
DHARMAWAN AUDELIA GUMARUS (SG)
XIONG YI (SG)
FOONG SHAOHUI (SG)
Application Number:
PCT/SG2020/050525
Publication Date:
March 25, 2021
Filing Date:
September 11, 2020
Export Citation:
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Assignee:
UNIV SINGAPORE TECHNOLOGY & DESIGN (SG)
International Classes:
B29C64/188; B29C64/118; B29C64/20; B29C64/393; B33Y10/00; B33Y30/00; B33Y40/00; B33Y50/00
Foreign References:
CN106002277A2016-10-12
CN108176912A2018-06-19
CN108145332A2018-06-12
CN106312574A2017-01-11
CN109394410A2019-03-01
Attorney, Agent or Firm:
VIERING, JENTSCHURA & PARTNER LLP (SG)
Download PDF:
Claims:
Claims

1. Apparatus for automated additive manufacturing of a three dimensional (3D) object comprising a platform having a surface on which the 3D object is to be constructed; a material deposition module having a deposition head for depositing a material, the deposition head movable relative to the surface of the platform along a deposition path to deposit a layer of the material at a layer height from the surface of the platform, the deposition path being based on a shape generated from a layer image of a CAD model of the 3D object sliced at the layer height from a base of the CAD model; a sensor arrangement disposed to scan and map a surface of the deposited layer of the material; a subtractive machining module having a machining tool, the machining tool movable relative to the surface of the platform to machine the surface of the deposited layer of the material based on comparing a surface roughness of the surface of the deposited layer of the material mapped by the sensor arrangement against a pre-set surface flatness tolerance, wherein the material deposition module sets a subsequent layer height for depositing a subsequent layer of the material based on a finished height of the deposited layer of the material from the surface of the platform.

2. The apparatus as claimed in claim 1, further comprising a robotic arrangement having at least one robot, wherein an end-effector of the at least one robot comprises at least one or both of the deposition head of the material deposition module and the machining tool of the subtractive machining module.

3. The apparatus as claimed in claim 2, wherein the robotic arrangement comprises a first robot and a second robot, wherein an end-effector of the first robot comprises the deposition head of the material deposition module and an end-effector of the second robot comprises the machining tool of the subtractive machining module.

4. The apparatus as claimed in claim 3, wherein the first robot comprises a serial manipulator and the second robot comprises a Cartesian robot. 5. The apparatus as claimed in any one of claims 1 to 4, wherein the sensor arrangement is movable to scan and map the surface of the deposited layer of the material.

6. The apparatus as claimed in claim 5 in combination with any one of claims 2 to 4, wherein the sensor arrangement is mounted to the robotic arrangement.

7. The apparatus as claimed in claim 5 in combination with any one of claims 3 or 4, wherein the sensor arrangement is mounted to the second robot.

8. The apparatus as claimed in any one of claims 1 to 7, wherein the material deposition module comprises a wire arc additive manufacturing module, and wherein the deposition head comprises a welding torch and a wire feeder.

9. The apparatus as claimed in any one of claims 1 to 8, wherein the subtractive machining module comprises a milling module, and wherein the machining tool comprises a milling tool.

10. The apparatus as claimed in any one of claims 1 to 9, wherein the sensor arrangement comprises at least one laser scanner.

11. The apparatus as claimed in any one of claims 1 to 10, further comprising a processor configured to control the movement of the deposition head relative to the surface of the platform to deposit the layer of the material, to control the operation of the sensor arrangement to scan and map the deposited layer of the material, and to control the movement of the machining tool relative to the surface of the platform to machine the surface of the deposited layer of the material.

12. The apparatus as claimed in claim 11 in combination with claim 3, wherein the processor is configured to control the first robot to move the deposition head along the deposition path.

13. The apparatus as claimed in claim 12, wherein the processor is configured to generate the deposition path in a coordinate frame of the deposition head from the deposition path in a coordinate frame of the platform generated from the layer image of the CAD model of the 3D object, a position of the platform in a coordinate frame of the first robot, and a position of the deposition head in a coordinate frame of the first robot.

14. The apparatus as claimed in claim 11 in combination with claim 3, wherein the processor is configured to control the second robot to move the machining tool along a machining path based on the shape generated from the layer image of the CAD model of the 3D object sliced at the layer height from a base of the CAD model.

15. The apparatus as claimed in claim 14, wherein the processor is configured to generate the machining path of the machining tool in a coordinate frame of the machining tool from the machining path in a coordinate frame of the platform generated from the layer image of the CAD model of the 3D object, a position of the platform in a coordinate frame of the first robot, a position of the second robot in the coordinate frame of the first robot, and a position of the machining tool in a coordinate frame of the second robot.

16. The apparatus as claimed in claim 11 in combination with claim 7, wherein the processor is configured to control the second robot to move the sensor arrangement for scanning and mapping the surface of the deposited layer of the material along a scanning path based on the shape generated from the layer image of the CAD model of the 3D object sliced at the layer height from a base of the CAD model.

17. The apparatus as claimed in claim 16, wherein the processor is configured to generate the scanning path of the sensor arrangement in a coordinate frame of the sensor arrangement from the scanning path in a coordinate frame of the platform generated from the layer image of the CAD model of the 3D object, a position of the platform in a coordinate frame of the first robot, a position of the second robot in the coordinate frame of the first robot and a position of the sensor arrangement in a coordinate frame of the second robot.

18. A method of constructing a three dimensional (3D) object via an apparatus for automated additive manufacturing, the method comprising: depositing a layer of a material at a layer height from a surface of a platform of the apparatus on which the 3D object is to be constructed by moving a deposition head of a material deposition module of the apparatus relative to the surface of the platform along a deposition path based on a shape generated from a layer image of a CAD model of the 3D object sliced at the layer height from a base of the CAD model; scanning and mapping, via a sensor arrangement of the apparatus, a surface of the deposited layer of the material by the material deposition tool; determining, based on comparing a surface roughness of the surface of the deposited layer of the material mapped by the sensor arrangement against a pre-set surface flatness tolerance, whether to move a machining tool of a subtractive machining module of the apparatus so as to machine the surface of the deposited layer of the material, setting a subsequent layer height for depositing a subsequent layer of the material by the deposition head of the material deposition module of the apparatus based on a finished height of the deposited layer of the material from the surface of the platform.

19. The method as claimed in claim 18, wherein the deposition head of the material deposition module is moved by a first robot along the deposition path and the machining tool of the subtractive machining module is moved by a second robot along a machining path, wherein an end-effector of the first robot comprises the deposition head of the material deposition module and an end-effector of the second robot comprises the machining tool of the subtractive machining module.

20. The method as claimed in claim 19, wherein scanning and mapping via the sensor arrangement of the apparatus comprises moving, via the second robot, the sensor arrangement along a scanning path to scan and map the surface of the deposited layer of the material, wherein the sensor arrangement is mounted to the second robot.

21. The method as claimed in claim 19, further comprising generating the deposition path in a coordinate frame of the deposition head to move the deposition head for depositing the layer of the material based on the deposition path in a coordinate frame of the platform generated from the layer image of the CAD model of the 3D object, a position of the platform in a coordinate frame of the first robot, and a position of the deposition head in a coordinate frame of the first robot.

22. The method as claimed in claim 19, further comprising generating the machining path of the machining tool in a coordinate frame of the machining tool to move the machining tool for machining the surface of the deposited layer of the material based on the machining path in a coordinate frame of the platform generated from the layer image of the CAD model of the 3D object, a position of the platform in a coordinate frame of the first robot, a position of the second robot in the coordinate frame of the first robot and a position of the machining tool in a coordinate frame of the second robot.

23. The method as claimed in claim 20, further comprising generating the scanning path of the sensor arrangement in a coordinate frame of the sensor arrangement to move the sensor arrangement for scanning and mapping the surface of the deposited layer of the material based on the scanning path in a coordinate frame of the platform generated from the layer image of the CAD model of the 3D object, a position of the platform in a coordinate frame of the first robot, a position of the second robot in the coordinate frame of the first robot and a position of the sensor arrangement in a coordinate frame of the second robot.

24. The method as claimed in claim 23, wherein the scanning path in the coordinate frame of the platform is generated from the layer image of the CAD model of the 3D object by extracting a bounding box enclosing an outline of the shape generated from the layer image, determining a number of pass for scanning based on a ratio of a width of the bounding box and a scanning width of the sensor arrangement, and generating the scanning path based on determining a center of each pass for scanning with respect to the width of the bounding box.

25. The method as claimed in any one of claims 18 to 24, further comprising providing the CAD model of the 3D object as an input to the apparatus.

26. The method as claimed in claims 25, further comprising slicing the CAD model of the 3D object into a plurality of layer images based on a predetermined vertical resolution, generating the deposition path for each of the plurality of layer images, and storing the generated deposition path in a library of the plurality of layer images.

27. The method as claimed in claim 26, further comprising retrieving the deposition path of the layer image at the layer height from the library of the plurality of layer images prior to depositing the layer of the material at the layer height.

28. The method as claimed in claim 26 or 27 in combination with claim 21 or 22, further comprising generating the machining path for each of the plurality of layer images, and storing the generated machining path in a library of the plurality of layer images.

29. The method as claimed in claim 28, further comprising retrieving the machining path of the layer image at the layer height from the library of the plurality of layer images prior to moving the machining tool of the subtractive machining module of the apparatus to machine the surface of the deposited layer of the material.

30. The method as claimed in claim 26 or 27 in combination with claim 20 and any one of claims 23 or 24, further comprising generating the scanning path for each of the plurality of layer images, and storing the generated scanning path in a library of the plurality of layer images.

31. The method as claimed in claim 30, further comprising retrieving the scanning path of the layer image at the layer height from the library of the plurality of layer images prior to moving, via the second robot, the sensor arrangement along the scanning path to scan and map the surface of the deposited layer of the material.

Description:
APPARATUS FOR AUTOMATED ADDITIVE MANUFACTURING OF A THREE DIMENSIONAU OBJECT AND A METHOD THEREOF

Technical Field [0001] Various embodiments generally relate to an apparatus for automated additive manufacturing (e.g. metal additive manufacturing) of a three dimensional object and a method of constructing a three dimensional object via an apparatus for automated additive manufacturing (e.g. metal additive manufacturing). Background

[0002] In recent years, metal Additive Manufacturing (AM) is gaining attention in fabrication of complex components for various industries. Compared with the traditional subtractive manufacturing, metal AM offers a shorter production time and requires less human intervention. It is also more cost-effective. Based on the feedstock type, metal AM can be categorized into powder-feed and wire-feed technology. Although powder- feed process can produce parts with higher accuracy, wire-feed approach is more practical for fabricating large components due to its higher deposition rate. The energy source for the deposition in wire-feed AM can be provided by an electron beam, a laser, or an electric arc. The arc-based technology, often referred to as Wire Arc Additive Manufacturing (WAAM), is generally less costly and has a higher deposition rate than the other two processes.

[0003] In WAAM, the parts are typically built by depositing overlapping weld beads in the horizontal (multi-bead) as well as vertical (multi-layer) directions on top of a substrate. The suitable distance between the beads in both horizontal (stepover increment) and vertical (layer increment) directions can be calculated from the experimental geometry of the single weld bead. Despite using the recommended stepover distance, it is still challenging to obtain a flat surface of the deposited layer, deteriorating the subsequent layer deposition. As the layers are built up vertically, the heat transfer conditions can also change. For the first few layers, the heat can quickly dissipate onto the larger substrate acting as a heat sink. For the subsequent layers, the heat conduction to the substrate is slower as it needs to pass through the previously deposited layers, leading to more accumulation of heat near the print. The different temperature conditions are generally known to affect the output behavior of the weld bead. The deposited layer at the different height level may have different layer thickness due to this varying cooling rate. This can lead to an accumulated error of the predicted cumulative printed height, thus affecting the accuracy of the set distance of the layer increment. A short distance between the welding nozzle and the layer surface can increase the chance of collision as well as spatters sticking onto the nozzle, while a long distance has been known to influence the shielding gas effect and can result in more porosities.

[0004] In order to solve the aforementioned issues, complex vision and control can be employed to regulate the welding parameters and the deposition to ensure the regularity and the accuracy of the printed layer thickness. However, such a feedback control requires developing a complicated online measurement system.

[0005] Accordingly, there is a need for a simpler, versatile and effective solution for automated additive manufacturing (e.g. metal additive manufacturing) of a three dimensional object.

Summary

[0006] According to various embodiments, there is provided an apparatus for automated additive manufacturing of a three dimensional (3D) object. The apparatus may include a platform having a surface on which the 3D object is to be constructed. The apparatus may include a material deposition module having a deposition head for depositing a material. The deposition head may be movable relative to the surface of the platform along a deposition path to deposit a layer of the material at a layer height from the surface of the platform. The deposition path may be based on a shape generated from a layer image of a CAD model of the 3D object sliced at the layer height from a base of the CAD model. The apparatus may include a sensor arrangement disposed to scan and map a surface of the deposited layer of the material. The apparatus may include a subtractive machining module having a machining tool. The machining tool may be movable relative to the surface of the platform to machine the surface of the deposited layer of the material based on comparing a surface roughness of the surface of the deposited layer of the material mapped by the sensor arrangement against a pre-set surface flatness tolerance. The material deposition module may set a subsequent layer height for depositing a subsequent layer of the material based on a finished height of the deposited layer of the material from the surface of the platform.

[0007] According to various embodiments, there is provided a method of constructing a three dimensional (3D) object via an apparatus for automated additive manufacturing. The method may include depositing a layer of a material at a layer height from a surface of a platform of the apparatus on which the 3D object is to be constructed by moving a deposition head of a material deposition module of the apparatus relative to the surface of the platform along a deposition path based on a shape generated from a layer image of a CAD model of the 3D object sliced at the layer height from a base of the CAD model. The method may include scanning and mapping, via a sensor arrangement of the apparatus, a surface of the deposited layer of the material by the material deposition tool. The method may include determining, based on comparing a surface roughness of the surface of the deposited layer of the material mapped by the sensor arrangement against a pre-set surface flatness tolerance, whether to move a machining tool of a subtractive machining module of the apparatus so as to machine the surface of the deposited layer of the material. The method may include setting a subsequent layer height for depositing a subsequent layer of the material by the deposition head of the material deposition module of the apparatus based on a finished height of the deposited layer of the material from the surface of the platform.

Brief description of the drawings

[0008] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments are described with reference to the following drawings, in which:

FIG. 1A shows a schematic diagram of an apparatus for automated additive manufacturing of a three dimensional (3D) object according to various embodiments;

FIG. IB shows a schematic diagram of the apparatus of FIG. 1A performing an additive operation according to various embodiments;

FIG. 1C shows a schematic diagram of the apparatus of FIG. 1A performing a scanning operation according to various embodiments; FIG. ID shows a schematic diagram of the apparatus of FIG. 1A performing a subtractive operation according to various embodiments;

FIG. 2 shows a schematic diagram of an apparatus for automated additive manufacturing of a three dimensional (3D) object according to various embodiments;

FIG. 3 shows a workflow diagram for the operation of the apparatus of FIG. 1 A and FIG. 2 according to various embodiments;

FIG. 4 shows a prototype of the apparatus of FIG. 1A and FIG. 2 according to various embodiments;

FIG. 5 shows a workflow diagram for the apparatus of FIG. 4 according to various embodiments;

FIG. 6 shows examples of the three different paths for the additive (deposition), registrative (scanning) and subtractive (machining) functions generated for manufacturing a test coupon par;

FIG. 7 shows the coordinate systems of the apparatus of FIG. 4 according to various embodiments;

FIG. 8A shows an illustration of the path planning of the apparatus of FIG. 4 for the laser scanning operation derived from the registrative path according to various embodiments;

FIG. 8B shows a pseudocode 888 of an algorithm for automating the path planning as illustrated in FIG. 8A according to various embodiments;

FIG. 9A shows an example of a block (or cube) printed by the apparatus of FIG. 4 according to various embodiments;

FIG. 9B shows a sample of the output of the laser scanner of the apparatus of FIG. 4 for one of the printed layer (9 th layer) of the printed block of FIG. 9A according to various embodiments;

FIG. 9C shows a cropped scan of the output shown in FIG. 9B according to various embodiments;

FIG. 9D shows a sample of a milled layer of the printed block of FIG. 9A according to various embodiments; and

FIG. 9E shows a plot of the actual average height of each of the printed layers of the printed block of FIG. 9A compared with the theoretical expected height according to various embodiments. Detailed description

[0009] Embodiments described below in the context of the apparatus are analogously valid for the respective methods, and vice versa. Furthermore, it will be understood that the embodiments described below may be combined, for example, a part of one embodiment may be combined with a part of another embodiment.

[00010] It should be understood that the terms “on”, “over”, “top”, “bottom”, “down”, “side”, “back”, “left”, “right”, “front”, “lateral”, “side”, “up”, “down” etc., when used in the following description are used for convenience and to aid understanding of relative positions or directions, and not intended to limit the orientation of any device, or structure or any part of any device or structure. In addition, the singular terms “a”, “an”, and “the” include plural references unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise.

[00011] In various embodiments, a "processor" may be understood as any kind of a logic implementing entity, which may be special purpose circuitry or a processor executing software stored in a memory, firmware, or any combination thereof. Thus, in an embodiment, a "processor" may be a hard-wired logic circuit or a programmable logic circuit such as a programmable processor, e.g. a microprocessor (e.g. a Complex Instruction Set Computer (CISC) processor or a Reduced Instruction Set Computer (RISC) processor). A "processor" may also be a processor executing software, e.g. any kind of computer program, e.g. a computer program using a virtual machine code such as e.g. Java. Any other kind of implementation of the respective functions which will be described in more detail below may also be understood as a "processor" in accordance with various embodiments. In various embodiments, the processor may be part of a computing system or a controller or a microcontroller or any other system providing a processing capability. According to various embodiments, such systems may include a memory which is for example used in the processing carried out by the device or system. A memory used in the embodiments may be a volatile memory, for example a DRAM (Dynamic Random Access Memory) or a non volatile memory, for example a PROM (Programmable Read Only Memory), an EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), or a flash memory, e.g., a floating gate memory, a charge trapping memory, an MRAM (Magneto-resistive Random Access Memory) or a PCRAM (Phase Change Random Access Memory). [00012] Various embodiments seek to provide an apparatus or system for automated additive manufacturing of a three dimensional (3D) object and a method of constructing 3D object via the apparatus for automated additive manufacturing. According to various embodiments, additive manufacturing may include creating or building or printing 3D objects by depositing and/or joining and/or adding and/or binding and/or solidifying materials in a layer by layer approach or in a layer upon layer manner. The materials may include metallic or ceramic or polymeric materials. According to various embodiments, the apparatus/system may perform additive manufacturing without human intervention after the apparatus/system is initiated to commence the additive manufacturing process (i.e. after the apparatus is started to build or construct the 3D object) and until the apparatus/system completes the additive manufacturing process (i.e. until the 3D object is completed). According to various embodiments, the apparatus/system and method may be configured for automated metal additive manufacturing. For example, various embodiments, may provide an apparatus/system and a method for automated wire-feed metal additive manufacturing using an electron beam, a laser, or an electric arc. According to various embodiments, the apparatus/system and method may be configured for automated arc-based additive manufacturing or automated Wire Arc Additive Manufacturing.

[00013] Various embodiments may provide an integrated apparatus or system for adaptive additive manufacturing (e.g. adaptive Hybrid-Wire Arc Additive Manufacturing (H- WAAM)) which may automatically sense, correct and update the print/build/construct behavior. The apparatus or system may include a first robot (e.g. a robot manipulator) equipped with an additive manufacturing module or a material deposition module (e.g. a welding system) to perform the additive operation (or deposition operation), and a second robot (e.g. a gantry system) equipped with a sensor arrangement (e.g. a laser displacement sensor) and a subtractive machining module (e.g. a milling head assembly installed) to perform the registrative operation (or scanning operation) and subtractive operation (or machining operation) respectively. Various embodiments may provide a universal framework which may be employed to automate the procedures of the additive operation (e.g. depositing), registrative operation (e.g. sensing) and subtractive operation (e.g. milling) from only a computer aided design (CAD) model of the desired 3D object. Human intervention may only be required for providing the CAD model and to start the apparatus or system. Various embodiments may accommodate for any desired 3D shape. [00014] Comparing to conventional Wire Arc Additive Manufacturing, various embodiments may provide a simpler solution which may include the step of face-milling of a printed/constructed/built layer to compensate for the thickness variation and to obtain surface evenness. Various embodiments may include an integrated sensing system/arrangement to automatically quantify the surface roughness and the required milling thickness as well as update the resulting layer height for the subsequent layer deposition. Various embodiments may provide an automated system capable of manufacturing all three-dimensional (3D) structures, for example 3D metal structures. According to various embodiments, there may be provided a more intelligent Wire Arc Additive Manufacturing apparatus and process requiring very minimal human intervention whereby it incorporates and automates the routines for constructing general 3D shapes. [00015] Various embodiment may provide a universal framework for an automated adaptive additive manufacturing (e.g. an automated adaptive Hybrid-Wire Arc Additive Manufacturing (H-WAAM)) apparatus/system. The only input required to the apparatus/system may be the CAD model of the 3D object to be built, and the apparatus/system may be able to automatically sense and adapt to the variation of the print/build/construct behavior to ensure the continuation and completion of the print/build/construct process. Specifically, the apparatus/system may be able to measure the current print/build/construct height after each layer is printed or built or constructed, decide whether subtractive operation is required to improve the smoothness of the top surface and perform accordingly, and finally update the actual height for the subsequent layer to be printed or built or constructed to obtain a more accurate finished workpiece. Various embodiments may be generic or general enough for printing or building or constructing any 3D object’s shape as it only requires the CAD model of the 3D object as the input. The capabilities of the apparatus/system and method of the various embodiments were demonstrated in various experiments conducted.

[00016] FIG. 1A shows a schematic diagram of an apparatus 100 (or a system) for automated additive manufacturing of a three dimensional (3D) object according to various embodiments. According to various embodiments, the apparatus 100 may be for automated adaptive additive manufacturing or automated adaptive metal additive manufacturing or automated adaptive Hybrid-Wire Arc Additive Manufacturing (H-WAAM). FIG. IB shows a schematic diagram of the apparatus 100 of FIG. 1A performing an additive operation according to various embodiments. FIG. 1C shows a schematic diagram of the apparatus 100 of FIG. 1A performing a scanning operation according to various embodiments. FIG. ID shows a schematic diagram of the apparatus 100 of FIG. 1A performing a subtractive operation according to various embodiments.

[00017] According to various embodiments, the apparatus 100 may include a platform 110 having a surface 112 on which the 3D object may be constructed or built or printed. According to various embodiments, the platform 110 may serve as a substrate or a base on which the 3D object may be formed. According to various embodiments, the platform 110 may include a table or a stage or a panel or a plate for a material 102 (for example, see FIG IB) to be deposited layer by layer. According to various embodiments, the surface 112 of the platform 110 may be a flat planar surface. According to various embodiments, the surface 112 of the platform 110 may be horizontal with respect to a ground and may be facing upwards.

[00018] According to various embodiments, the apparatus 100 may include a material deposition module 120 having a deposition head 122 for depositing the material 102. Accordingly, the deposition head 122 of the material deposition module 120 may perform the additive operation of the apparatus 100 for constructing or building or printing the 3D object. According to various embodiments, the material 102 may be any material suitable for additive manufacturing including, but not limited to, metal, ceramics and polymeric materials. According to various embodiments, the deposition head 122 of the material deposition module 120 may be a component of the material deposition module 120 to dispense or discharge or provide or supply the material 102 and/or to place or lay or pile the material 102. According to various embodiments, the material deposition module 120 may include a material source 124. The material source 124 may be another component of the material deposition module 120. The material source 124 of the material deposition module 120 may include, but not limited to, a material tank, a material reservoir, a wire-feed arrangement, or a powder-feed arrangement. According to various embodiments, a tip 122a of the deposition head 122 may serve as an exit point or a point of release or a discharge point for the material 102 to be delivered or freed or let out from the material deposition module 120. According to various embodiments, the deposition head 122 of the material deposition module 120 may be operated based on a deposition-control signal to deposit the material. According to various embodiments, the material deposition module 120 may include various other components 126 for processing the material 102 to perform the additive operation. For example, the other components 126 of the material deposition module 120 may include, but not limited to, a heating arrangement to heat the material such that the material is in a state or possesses the properties suitable for additive operation, or a conveying arrangement to move or transport or carry the material through the various components of the material deposition module 120 from the material source 124 to the deposition head 122.

[00019] According to various embodiments, the deposition head 122 may be movable relative to the surface 112 of the platform 110 along a deposition path (or an additive path) to deposit a layer of material 102 at a layer height from the surface 112 of the platform 110. Accordingly, the deposition head 122 may move along a deposition plane parallel to the surface 112 of the platform 110. When the deposition head 122 is moving along the deposition plane, the tip 122a of the deposition head 122 may be spaced apart from the surface 112 of the platform 110 at a height equal or greater than the layer height measured from the surface of the platform 110. Further, the deposition head 122 may be moved to bring the tip 122a of the deposition head 122 to the height prior to moving along the deposition plane parallel to the surface 112 of the platform 110. According to various embodiments, the deposition head 122 may be operable to dispense or discharge or provide or supply the material as the deposition head 122 moves relative to the surface 122 of the platform 110 in a manner so as to place or lay or pile the material 102 to form or accumulate the material 102 into the layer of material 102. Accordingly, the deposition head 122 may be operable to deposit the layer of material 102 at the layer height.

[00020] According to various embodiments, the deposition path of the deposition head 122 may be based on a shape generated from a layer image of a computer aided design (CAD) model of the 3D object sliced at the layer height from a base of the CAD model. Accordingly, the CAD model of the desired 3D object to be constructed or built or printed may be provided as an input to the apparatus 100. The CAD model may be sliced into a plurality of layer images at a predetermined vertical resolution from the base of the CAD model. The predetermined vertical resolution may be based on a user-defined parameter depending on the required accuracy. According to various embodiments, each layer image may contain the shape which corresponds to a cross section shape of the CAD model of the 3D object when cut or slice at that layer height. According to various embodiments, depending on the 3D object, the shape generated in each layer image of the CAD model of the 3D object may be different. According to various embodiments, the deposition path may guide the deposition head 122 to deposit the layer of the material 102 in a manner so as to form the shape in the layer image of the CAD model of the 3D object which corresponds to the layer height. According to various embodiments, the deposition path may be confined within the shape in the layer image of the CAD model of the 3D object. According to various embodiments, the deposition path may be of any types of path pattern including, but not limited to, contour-based path pattern (e.g. spiral) or raster path pattern (e.g. zigzag). According to various embodiments, a stepover distance of the deposition path may be based on the material 102 to be deposited. The stepover distance may be a perpendicular distance between two adjacent parallel segments of the deposition path.

[00021] According to various embodiments, the material deposition module 120 may include an inbuilt motion mechanism for moving the deposition head 122 (as another component of the material deposition module 120) or the deposition head 122 of the material deposition module 120 may be coupled to an external robotic arrangement 250 (for example, see FIG. 2) for moving the deposition head 122. According to various embodiments, the inbuilt motion mechanism or the external robotic arrangement 250 may move the deposition head 122 of the material deposition module 120 based on a movement-control signal. The movement-control signal may include, but not limited to, a signal to move the deposition head 122 to a starting position of the deposition path, a signal or a series of signals to move the deposition head 122 along the deposition path, and/or a signal to retract the deposition head 122 after the additive operation is completed.

[00022] According to various embodiments, the apparatus 100 may include a sensor arrangement 130 disposed to scan and map a surface 104 of the deposited layer of the material 102, which is deposited by the material deposition module 120. According to various embodiments, the sensor arrangement 130 may include at least one sensor 132, or one or more sensors 132. According to various embodiments, the sensor 132 of the sensor arrangement 130 may include, but not limited to, anyone or a combination of an acoustic sensor, light sensor, optical sensor, laser sensor, infra-red sensor, imaging sensor, photon sensor, etc. According to various embodiments, the at least one sensor 132, or one or more sensors 132, of the sensor arrangement 130 may be arranged and configured to scan a profile or a contour of a target surface in various manner, including, but not limited to, any one or a combination of single point profile scanning, or multi-point profile scanning, or line profile scanning, or area profile scanning, or confocal scanning, or LiDAR (light detection and ranging) scanning. According to various embodiments, the sensor arrangement 130 may be operated based on a scanning-control signal. According to various embodiments, the sensor arrangement 130 may be disposed based on the configuration of the type of sensors and/or the type of scanning. For example, when the sensor arrangement 130 is configured for area profile scanning or LiDAR scanning, the sensor arrangement 130 may be disposed in a fixed position with respect to the surface 112 of the platform 110. As another example, when the sensor arrangement 130 is configured for single point profile scanning, or multi point profile scanning, or line profile scanning, or confocal scanning, the sensor arrangement 130 may be disposed so as to be movable relative to the surface 112 of the platform 110.

[00023] According to various embodiments, the surface 104 of the deposited layer of the material 102 scanned and mapped by the sensor arrangement 130 may be an upward facing surface (or top surface) of the deposited layer of the material 102. Accordingly, the upward facing surface of the deposited layer of material 102 may be a surface that is facing or directed away from the surface 112 of the platform 110. Hence. The upward facing surface of the deposited layer of material 102 may be parallel to the surface 112 of the platform 110. According to various embodiments, the surface 104 of the deposited layer of the material 102 scanned and mapped by the sensor arrangement 130 may be a side surface of the deposited layer of the material 102. Accordingly, the side surface of the deposited layer of the material 102 may be at least substantially perpendicular to the surface 112 of the platform 110. According to various embodiments, the sensor arrangement 130 may be disposed and configured to scan and map one or more surfaces 104 of the deposited layer of the material 102. For example, the one or more surfaces 104 of the deposited layer of the material 102 may include any one or a combination of the upward facing surface and the side surfaces of the deposited layer of the material 102. According to various embodiments, depending on the surface or surfaces to be scanned and mapped, the sensor arrangement 130 may be disposed and configured accordingly.

[00024] According to various embodiments, the sensor arrangement 130 may scan the surface 104 of the deposited layer of the material 102 and generate surface topology data including, but not limited to, thickness, height, surface roughness, positions, etc., for the entire surface 104. The surface topology data generated may be mapped into or represented by a two dimensional (2D) intensity image which can be subsequently analyzed and/or processed. Accordingly, mapping of the surface 104 of the deposited layer of the material 102 may include compiling and transforming the surface topology data obtained via scanning into the 2D intensity image. [00025] According to various embodiments, the apparatus 100 may include a subtractive machining module 140 having a machining tool 142 for machining the surface 104 of the deposited layer of material 102. Accordingly, the machining tool 142 of the subtractive machining module 140 may be a component of the subtractive machining module 140 to perform the subtractive operation of the apparatus 100 for trimming or shaving or cutting the surface 104 of the deposited layer of material 102 so as to level or flatten or smoothen or straighten the surface 104 of the deposited layer of material 102. According to various embodiments, the subtractive operation may include, but not limited to, turning, milling, broaching, shaping, planning, grinding, or laser cutting. Accordingly, depending on the type of subtractive operation performed by the subtractive machining module 140, the machining tool 142 may include a corresponding cutting tool or the machining tool 142 may be configured accordingly to perform the required subtractive operation. According to various embodiments, the subtractive machining module 140 may include a driving unit 144 to impart motion to the machining tool 142 for performing the subtractive operation. The driving unit 144 may be another component of the subtractive machining module 140. The driving unit 144 of the subtractive machining module 140 may include, but not limited to, a motor, an actuator, a rotary actuator, or a linear actuator. Accordingly, depending on the type of subtractive operation performed by the subtractive machining module 140, the driving unit 144 may include a suitable motor or actuator, or may be configured accordingly to provide the necessary motion to move the machining tool 142 for performing the subtractive operation. According to various embodiments, the driving unit 144 may impart motion to the machining tool 142 for machining based on a drive-control signal. According to various embodiments, the subtractive machining module 140 may include various other components 146 for performing the subtractive operation. For example, the other components 146 of the subtractive machining module 140 may include, but not limited to, a transmission arrangement for transmitting the motion of the driving unit 144 to the machining tool 142.

[00026] According to various embodiments, the machining tool 142 may be movable relative to the surface 112 of the platform 110 to machine the surface 104 of the deposited layer of the material 102 based on comparing a surface roughness of the surface 104 of the deposited layer of the material 102 mapped by the sensor arrangement 130 against a pre-set surface flatness tolerance. Accordingly, the machining tool 142 may move along a machining plane parallel to the surface 112 of the platform 110. When the machining tool 142 is moving along the machining plane, the machining tool 142 may be spaced apart from the surface 112 of the platform 110.

[00027] According to various embodiments, the surface roughness of the surface 104 of the deposited layer of the material 102 may be obtained from the two dimensional (2D) intensity image and/or the surface topology data from the sensor arrangement 130. According to various embodiments, the pre-set surface flatness tolerance may be defined based on a specified distance between two parallel planes. Accordingly, when all the surface topology data of the surface 104 of the deposited layer of the material 102 fall in between the specified distance between the two parallel planes of the pre-set surface flatness tolerance, the surface 104 of the deposited layer of the material 102 may be considered to be within the pre-set surface flatness tolerance and the pre-set surface flatness tolerance is considered met. On the other hand, when at least one data point of the surface topology data of the surface 104 of the deposited layer of the material 102 fall outside the two parallel planes of the pre-set surface flatness tolerance, the surface 104 of the deposited layer of the material 102 may be considered not to satisfy the pre-set surface flatness tolerance and the pre-set surface flatness tolerance is breached or violated or unmet. According to various embodiments, to determine whether the surface roughness of the surface 104 of the deposited layer of the material 102 meets the pre-set surface flatness tolerance or violates the pre-set surface flatness tolerance, a vertical distance between a lowest point and a highest point of the surface roughness of the surface 104 of the deposited layer of the material 102 may be compared to the specified distance between the two parallel planes of the pre-set surface flatness tolerance. When the vertical distance between a lowest point and a highest point of the surface roughness of the surface 104 of the deposited layer of the material 102 is equal or lesser than the specified distance between the two parallel planes of the pre-set surface flatness tolerance, the surface roughness of the surface 104 of the deposited layer of the material 102 fits the pre-set surface flatness tolerance and the pre-set surface flatness tolerance is met. When the vertical distance between the lowest point and the highest point of the surface roughness of the surface 104 of the deposited layer of the material 102 is greater than the specified distance between the two parallel planes of the pre-set surface flatness tolerance, the surface roughness of the surface 104 of the deposited layer of the material 102 breaches or violates the pre-set surface flatness tolerance and the pre-set surface flatness tolerance is unmet. [00028] According to various embodiments, the subtractive machining module 140 may be activated and operated to move the machining tool 142 to machine the surface 104 of the deposited layer of the material 102 when the surface roughness of the surface 104 of the deposited layer of the material 102 breaches or violates the pre-set surface flatness tolerance. According to various embodiments, the subtractive machining module 140 may not be activated and operated to move the machining tool 142 to machine the surface 104 of the deposited layer of the material 102 when the surface roughness of the surface 104 of the deposited layer of the material 102 meets the pre-set surface flatness tolerance. Accordingly, the apparatus 100 may be adaptive in that the apparatus 100 may determine whether to machine the surface 104 of the deposited layer of the material 102 depending on the whether the surface roughness of the surface 104 of the deposited layer of the material 102 meets the pre-set surface flatness tolerance.

[00029] According to various embodiments, the pre-set surface flatness tolerance may be defined based on an expected thickness of the deposited layer of the material 102. According to various embodiments, the pre-set surface flatness tolerance may be defined as a ratio of the expected thickness of the deposited layer of the material 102. According to various embodiments, the pre-set surface flatness tolerance may be a user-defined parameter. [00030] According to various embodiments, when subtractive operation is required, the subtractive machining module 140 may be activated and operated to move the machining tool 142 to machine the surface 104 of the deposited layer of the material 102 with a machining depth based on the surface roughness of the surface 104 of the deposited layer of the material 102. For example, the machining depth may be equal to the vertical distance between the lowest point and the highest point of the surface roughness of the surface 104 of the deposited layer of the material 102 minus the pre-set surface flatness tolerance, and a datum reference for machining may be the highest point of the surface roughness of the surface 104 of the deposited layer of the material 102. As another example, the machining depth may be equal to the vertical distance between the lowest point and the highest point of the surface roughness of the surface 104 of the deposited layer of the material 102 and a datum reference for machining may be the highest point of the surface roughness of the surface 104 of the deposited layer of the material 102. As yet another example, the machining depth may be equal to half the vertical distance between the lowest point and the highest point of the surface roughness of the surface 104 of the deposited layer of the material 102 and a datum reference for machining may be the highest point of the surface roughness of the surface 104 of the deposited layer of the material 102.

[00031] According to various embodiments, the machining tool 142 may be movable relative to the surface 112 of the platform 110 along a machining path (or a subtractive path) to machine the surface 104 of the deposited layer of the material 102. According to various embodiments, the machining path of the machining tool 142 may be based on the shape generated from the layer image of the CAD model of the 3D object sliced at the layer height from the base of the CAD model. Accordingly, the machining path of the machining tool 142 and the deposition path of the deposition head 122 may be based on the same shape from the same layer image of the CAD model of the 3D object at the same layer height. Since the layer of material 102 is deposited by the deposition head 122 based on the deposition path, setting the machining path of the machining tool 142 based on the same shape generated from the same layer image of the CAD model of the 3D object sliced at the same layer height may ensure that the machining path correspond to the deposited layer of material 102 and that the machining tool 142 machine the surface of the deposited layer of material 102. According to various embodiments, the machining path may guide the machining tool 142 to machine the surface of the deposited layer of material 102 in a manner so as to level or flatten or smoothen or straighten the surface 104 of the deposited layer of material 102. According to various embodiments, the machining path may be confined within the shape in the layer image of the CAD model of the 3D object at the layer height. According to various embodiments, the machining path may be of any types of path pattern including, but not limited to, contour-based path pattern (e.g. spiral) or raster path pattern (e.g. zigzag). According to various embodiments, a stepover distance of the machining path may be based on the machining tool 142. The stepover distance may be a perpendicular distance between two adjacent parallel segments of the machining path.

[00032] According to various embodiments, the subtractive machining module 140 may include an inbuilt motion mechanism for moving the machining tool 142 (as another component of the subtractive machining module 140) or the machining tool 142 of the subtractive machining module 140 may be coupled to the external robotic arrangement 250 for moving the machining tool 142. According to various embodiments, the inbuilt motion mechanism or the external robotic arrangement 250 may move the machining tool 142 of the subtractive machining module 140 based on a movement-control signal. The movement- control signal may include, but not limited to, a signal to move the machining tool 142 to a starting position of the machining path, a signal or a series of signals to move the machining tool 142 along the deposition path, and/or a signal to retract the machining tool 142 after the subtractive operation is completed.

[00033] According to various embodiments, the material deposition module 120 may set a subsequent layer height for depositing a subsequent layer of the material 102 based on a finished height of the deposited layer of the material 102 from the surface 112 of the platform 110. Accordingly, when the subtractive operation is performed by the apparatus 100, the finished height of the deposited layer of the material 102 may be based on the highest point of the surface roughness of the surface 104 of the deposited layer of the material 102 minus the machining depth of the subtractive operation. On the other hand, when the subtractive operation is not performed by the apparatus 100, the finished height of the deposited layer of the material 102 may be based on the highest point of the surface 104 of the deposited layer of the material 102. According to various embodiments, the apparatus 100 may be adaptive in that the apparatus 100 deposit the subsequent layer of the material based on the finished height of the currently deposited layer of the material 102. Accordingly, the actual 3D object constructed by the apparatus 100 may achieve its full desired height as the apparatus 100 may continue to construct the 3D object if the finished height of the currently deposited layer of the material 102 has not reach the desired height of the 3D object.

[00034] According to various embodiments, depending on the type of scanning profile, the sensor arrangement 130 may be movable relative to the surface 112 of the platform 110 so as to scan and map the surface 104 of the deposited layer of the material 102. According to various embodiments, the sensing arrangement 130 may be coupled to the deposition head 122 of the material deposition module 120, or the machining tool 142 of the subtractive machining module 140, or the external robotic arrangement 250 for moving the sensing arrangement 130. According to various embodiments, the material deposition module 120 or the subtractive machining module 140 or the external robotic arrangement 250 may move the sensing arrangement 130 based on a movement-control signal. The movement-control signal may include, but not limited to, a signal to move the sensing arrangement 130 to a starting position of a scanning path, a signal or a series of signals to move the sensing arrangement 130 along the scanning path, and/or a signal to retract the sensing arrangement 130 after the scanning operation is completed. [00035] According to various embodiments, the external robotic arrangement 250 may include at least one robot. According to various embodiments, the external robotic arrangement 250 may include one robot or two robots. According to various embodiments, an end-effector of the at least one robot may include at least one or any combination of the deposition head 122 of the material deposition module 120, the machining tool 142 of the subtractive machining module 140, and the sensor arrangement 130. Accordingly, at least one or any combination of the deposition head 122 of the material deposition module 120, the machining tool 142 of the subtractive machining module 140, and the sensor arrangement 130 may form the end-effector of the at least one robot or may be coupled to the end-effector of the at least one robot or may be disposed at the end-effector of the at least one robot.

[00036] According to various embodiments, depending on the number of robots included in the robotic arrangement 250, the end-effector of the respective robots may include various permutations and/or combinations of the deposition head 122 of the material deposition module 120, the machining tool 142 of the subtractive machining module 140, and the sensor arrangement 130. For example, when the robotic arrangement 250 includes one robot and the sensor arrangement 130 is fixed, the end-effector of the robot of the robotic arrangement 250 may include both the deposition head 122 of the material deposition module 120 and the machining tool 142 of the subtractive machining module 140. As another example, when the robotic arrangement 250 includes one robot and the sensor arrangement 130 is movable, the end-effector of the robot of the robotic arrangement 250 may include the deposition head 122 of the material deposition module 120, the machining tool 142 of the subtractive machining module 140, and the sensor arrangement 130. As yet another example, when the robotic arrangement 250 includes two robots and the sensor arrangement 130 is fixed, an end-effector of a first robot of the robotic arrangement 250 may include the deposition head 122 of the material deposition module 120 and an end- effector of a second robot of the robotic arrangement 250 may include the machining tool 142 of the subtractive machining module 140. As a further example, when the robotic arrangement 250 includes two robots and the sensor arrangement 130 is movable, the end- effector of the first robot of the robotic arrangement 250 may include the deposition head 122 of the material deposition module 120, the end-effector of the second robot of the robotic arrangement 250 may include the machining tool 142 of the subtractive machining module 140, and the sensor arrangement 130 may be at the end-effector of the first robot or the end-effector of the second robot.

[00037] According to various embodiments, the apparatus 100 may further include a processor 260 (for example, see FIG. 2). According to various embodiments, the processor 260 may be configured to control the movement of the deposition head 122 relative to the surface 112 of the platform 110 to deposit the layer of the material 102, to control the operation of the sensor arrangement 130 to scan and map the deposited layer of the material 102, and to control the movement of the machining tool 142 relative to the surface 112 of the platform 110 to machine the surface 104 of the deposited layer of the material 102. According to various embodiments, the processor 260 may be configured to generate the various control signals, such as deposition-control signal, movement-control signal, drive- control signal, scanning-control signal, etc. for operating the various combination of components of the apparatus 100. According to various embodiments, the processor 260 may communicate the various control signals to respective local controller of the various components of the apparatus 100 for executing the actions based on the control signals. According to various embodiments, the processor 260 may be configured to generate the various control signals so as to operate the apparatus 100 in accordance to the various methods as described herein. According to various embodiments, the processor 260 may be configured to generate the various control signals in a pre-determined sequence and/or predetermined response based on the various methods as described herein. According to various embodiments, the processor 260 may generate the control signal to control the movement of the deposition head 122 relative to the surface 112 of the platform 110 to deposit the layer of the material; generate the control signal to control the operation of the sensor arrangement 130 to scan and map the deposited layer of the material 104; process the data from the sensor arrangement 130 to determine whether to activate the machining tool 142 to machine the surface 104 of the deposited layer of material 102; generate, if required, control signal to control the movement of the machining tool 142 relative to the surface 112 of the platform 110 to machine the surface 104 of the deposited layer of the material 102; and set the subsequent layer height for generating the subsequent control signal to control the movement of the deposition head 122 relative to the surface 112 of the platform 110 to deposit the subsequent layer of the material.

[00038] FIG. 2 shows a schematic diagram of an apparatus 200 (or a system) for automated additive manufacturing of a three dimensional (3D) object according to various embodiments. According to various embodiments, the apparatus 200 of FIG. 2 may be an example of the apparatus 100 of FIG. 1A to FIG. ID, wherein the external robotic arrangement 250 may include a first robot 252 and a second robot 254. According to various embodiments, the apparatus 200 may, similar to the apparatus 100 of FIG. 1A to FIG. ID, be for automated adaptive additive manufacturing or automated adaptive metal additive manufacturing or automated adaptive Hybrid-Wire Arc Additive Manufacturing (H- WAAM). According to various embodiments, in the example as represented by apparatus 200 of FIG. 2, the apparatus 200 may, similar to the apparatus 100 of FIG. 1A to FIG. ID, include the platform 110, the material deposition module 120, the sensor arrangement 130, the subtractive machining module 140, the robotic arrangement 250, and the processor 260. [00039] According to various embodiments, in the example as represented by the apparatus 200 of FIG. 2, an end-effector of the first robot 252 may include the deposition head 122 of the material deposition module 120 and an end-effector of the second robot 254 may include the machining tool 142 of the subtractive machining module 140. Accordingly, the deposition head 122 of the material deposition module 120 may form the end-effector of the first robot 252 or may be coupled to the end-effector of the first robot 252 or may be disposed at the end-effector of the first robot 252. Similarly, the machining tool 142 of the subtractive machining module 140 may form the end-effector of the second robot 254 or may be coupled to the end-effector of the second robot 254 or may be disposed at the end- effector of the second robot 254. Accordingly, the first robot 252 may move the deposition head 122 of the material deposition module 120 for depositing the layer of material 102 and the second robot 254 may move the machining tool 142 of the subtractive machining module 140 for machining the surface 104 of the deposited layer of material 102.

[00040] According to various embodiments, each of the first robot 252 or the second robot 254 may include a serial manipulator or a Cartesian robot. According to various embodiments, the serial manipulator may include a robotic arm having a chain of links connected by motor-actuated joints wherein an end-effector is at the end of the chain. For example, the serial manipulator may include, but not limited to, an industrial robotic arm, or an assembly robotic arm, or a SCARA (Selective Compliance Articulated Robot Arm) robot. According to various embodiments, the Cartesian robot may include three sliding joints whereby the three sliding axes are linear and perpendicular to each other. Accordingly, an end-effector of the Cartesian robot may move linearly along the three sliding axes. Hence, the end-effector of the Cartesian robot may perform 3 -axis (x, y, and z) linear movement. According to various embodiments, the Cartesian robot may be of an overhead configuration such that it is movable over and across the surface 112 of the platform 110. According to various embodiments, the Cartesian robot may include a gantry robot or an industrial linear robot.

[00041] According to various embodiments, the robotic arrangement 250 may include various combinations of the first robot 252 and the second robot 254. For example, the first robot 252 may include the serial manipulator and the second robot 254 may include the Cartesian robot. As another example, the first robot 252 may include the Cartesian robot and the second robot 254 may include the serial manipulator. As yet another example, both the first and second robots 252, 254 may be serial manipulators. As a further example, both the first and second robots 252, 254 may be Cartesian robots.

[00042] According to various embodiments, the sensor arrangement 130 may be mounted to the robotic arrangement 250 for moving the sensor arrangement 130 to scan and map the surface 104 of the deposited layer of the material 102. According to various embodiments, when the robotic arrangement 250 include the first robot 252 and the second robot 254 as represented in the example as shown in FIG. 2, the sensor arrangement 130 may be mounted to the first robot 252 or the second robot 254 or both.

[00043] According to various embodiments, as represented in the examples as shown in FIG. 2, the processor 260 may be wired or wirelessly coupled to the material deposition module 120, the sensor arrangement 130, the subtractive machining module 140, the first robot 252 and the second robot 254.

[00044] According to various embodiments, the processor 260 may be configured to control the first robot 252 to move the deposition head 122 along the deposition path. According to various embodiments, the processor 260 may generate the deposition path based on the shape from the layer image of the CAD model of the 3D object sliced at the layer height from the base of the CAD model. According to various embodiments, the processor 260 may generate movement-control signal based on the deposition path to control the first robot 252 to move the deposition head 122 along the deposition path. [00045] According to various embodiments, the processor 260 may generate the deposition path in a coordinate frame of the deposition head 122 from the deposition path in a coordinate frame of the platform 110 generated from the layer image of the CAD model of the 3D object, a position of the platform 110 in a coordinate frame of the first robot 252, and a position of the deposition head 122 in the coordinate frame of the first robot 252. According to various embodiments, the processor 260 may generate movement-control signal based on the deposition path in the coordinate frame of the deposition head 122 to move the deposition head 122 for depositing the layer of the material 102.

[00046] According to various embodiments, the processor 260 may be configured to control the second robot 254 to move the machining tool 142 along the machining path. According to various embodiments, the processor 260 may generate the machining path based on the shape generated from the layer image of the CAD model of the 3D object sliced at the layer height from a base of the CAD model. According to various embodiments, the processor 260 may generate movement-control signal based on the machining path to control the second robot 254 to move the machining tool 142 along the machining path. [00047] According to various embodiments, the processor 260 may be configured to generate the machining path of the machining tool 142 in a coordinate frame of the machining tool from the machining path in the coordinate frame of the platform 110 generated from the layer image of the CAD model of the 3D object, the position of the platform 110 in the coordinate frame of the first robot 252, a position of the second robot 254 in the coordinate frame of the first robot 252, and a position of the machining tool 142 in a coordinate frame of the second robot 254. According to various embodiments, the processor 260 may generate movement-control signal based on the machining path in the coordinate frame of the machining tool 142 to move the machining tool 142 for machining the surface 104 of the deposited layer of the material 102.

[00048] According to various embodiments, when the sensor arrangement 130 is mounted to the second robot 254, the processor 260 may be configured to control the second robot 254 to move the sensor arrangement 130 for scanning and mapping the surface 104 of the deposited layer of the material 102 along a scanning path based on the shape generated from the layer image of the CAD model of the 3D object sliced at the layer height from a base of the CAD model. According to various embodiments, the processor 260 may generate movement-control signal based on the scanning path to control the second robot 254 to move the sensor arrangement 130 along the scanning path.

[00049] According to various embodiments, when the sensor arrangement 130 is mounted to the second robot 254, the processor 260 may be configured to generate the scanning path of the sensor arrangement 130 in a coordinate frame of the sensor arrangement 130 based on the scanning path in the coordinate frame of the platform 110 generated from the layer image of the CAD model of the 3D object, the position of the platform 110 in a coordinate frame of the first robot 252, the position of the second robot 254 in the coordinate frame of the first robot 252 and a position of the sensor arrangement 130 in the coordinate frame of the second robot 254. According to various embodiments, the processor 260 may generate movement-control signal based on the scanning path in the coordinate frame of the sensor arrangement 130 to move the sensor arrangement 130 for scanning and mapping the surface 104 of the deposited layer of the material 102.

[00050] According to various embodiments, the processor 260 may be configured to generate the scanning path in the coordinate frame of the platform 110 from the layer image of the CAD model of the 3D object by extracting a bounding box enclosing an outline of the shape from the layer image, determining a number of pass for scanning based on a ratio of a width of the bounding box and a scanning width of the sensor arrangement 130, and generating the scanning path based on determining a center of each pass for scanning with respect to the width of the bounding box. According to various embodiments, the scanning path in the coordinate frame of the platform 110 may be processed for the generation of the scanning path of the sensor arrangement 130 in the coordinate frame of the sensor arrangement 130.

[00051] According to various embodiments, when the sensor arrangement 130 is mounted to the first robot 252, the processor 260 may be configured to control the first robot 252 and to generate the scanning path accordingly.

[00052] According to various embodiments, the processor 260 may be configured to determine whether to machine the surface 104 of the deposited layer of material 102 based on comparing the surface roughness of the surface 104 of the deposited layer of the material 102 mapped by the sensor arrangement 130 against the pre-set surface flatness tolerance. According to various embodiments, the processor 260 may be configured to control the second robot 254 to move the machining tool 142 along the machining path for machining the surface 104 of the deposited layer of the material 102 when the pre-set surface flatness tolerance is not met by the surface roughness of the surface 104 of the deposited layer of the material 102. According to various embodiments, when the pre-set surface flatness tolerance is met by the surface roughness of the surface 104 of the deposited layer of the material 102, the processor 260 may be configured to skip the control of the second robot 254 for moving the machining tool 142.

[00053] FIG. 3 shows a workflow diagram 300 for the operation of the apparatus 100, 200 according to various embodiments. According to various embodiments, at 301, the CAD model of the 3D object may be provided as an input to the apparatus 100, 200. According to various embodiments, the CAD model of the 3D object may be provided to the processor 260 of the apparatus 100, 200. According to various embodiments, at 303, the CAD model of the 3D object may be sliced into the plurality of layer images based on the predetermined vertical resolution. Accordingly, the processor 260 may be configured to process the CAD model of the 3D object to slice the CAD model according to the predetermined vertical resolution into the plurality of layer images. According to various embodiments, the predetermined vertical resolution may be based on a user-defined parameter depending on the required accuracy. According to various embodiments, each layer image may contain the shape which corresponds to the cross section shape of the CAD model of the 3D object when cut or slice at that layer height. According to various embodiments, the plurality of layer images may be stored as a library of the plurality of layer images by the processor 260. [00054] According to various embodiments, at 303, the processor 260 may generate the deposition path for each of the plurality of layer images and store the generated deposition path in the library of the plurality of layer images. According to various embodiments, at 303, the processor 260 may generate the machining path for each of the plurality of layer images and store the generated machining path in the library of the plurality of layer images. According to various embodiments, at 303, the processor 260 may generate the scanning path for each of the plurality of layer images and store the generated scanning path in the library of the plurality of layer images.

[00055] According to various embodiments, at 305, the workflow may start with the processor 260 retrieving the deposition path of the layer image for the base layer of the CAD model from the library of the plurality of layer images.

[00056] According to various embodiments, at 307, with the deposition path retrieved from the library of the plurality of layer images, the processor may control the first robot 252 to move the deposition head 122 of the material deposition module 120 to deposit a first layer of the material 102 on the surface 112 of the platform 110 based on the deposition path.

[00057] According to various embodiments, at 309, upon completion of the deposition of the first layer of the material 102, the processor 260 may retrieve the scanning path of the layer image for the base layer of the CAD model from the library of the plurality of layer images. For example, when the sensor arrangement 130 is mounted to the second robot 254, the processor 260 may then control the second robot 254 to move the sensor arrangement 130 along the scanning path to scan and map the surface 104 of the first deposited layer of the material 102.

[00058] According to various embodiments, at 311 , with the data obtained from the sensor arrangement 130, the processor 260 may compare the surface roughness of the surface 104 of the first deposited layer of the material 102 mapped by the sensor arrangement 130 against the pre-set surface flatness tolerance.

[00059] According to various embodiments, if the pre-set surface flatness tolerance is determined to be met at 311, the processor 260 may set the layer height for the subsequent layer height based on the finished height of the first deposited layer of the material 102. [00060] According to various embodiments, if the pre-set surface flatness tolerance is determined to be not met at 311, the processor 260 may, at 315, retrieve the machining path of the layer image for the base layer of the CAD model from the library of the plurality of layer images. The processor 260 may then control the second robot 254 to move the machining tool 142 of the subtractive machining module 140 to machine the surface 104 of the first deposited layer of the material 102. At 313, the processor 260 may set the subsequent layer height for the subsequent layer height based on the finished height after machining the first deposited layer of the material 102.

[00061] According to various embodiments, at 317, the processor 260 may check whether the subsequent layer height is the last layer of the CAD model of the 3D object from the library of the plurality of the layer images.

[00062] According to various embodiments, if the subsequent layer height is not the last layer of the CAD model of the 3D object, the processor 260 may, at 303, retrieve the deposition path of the layer image of the subsequent layer height from the library of the plurality of layer images.

[00063] According to various embodiments, at 319, the processor 260 may set the current layer height based on the previously determined subsequent layer height and repeat the process and steps from 307 to 317 based on the current layer height.

[00064] According to various embodiments, at 317, if the subsequent layer height is the last layer of the CAD model of the 3D object, the processor 260 may end the additive manufacturing process at 321.

[00065] FIG. 4 shows a prototype of an apparatus 400 (or a system or an integrated system) for automated additive manufacturing of a three dimensional (3D) object according to various embodiments. According to various embodiments, the apparatus 400 of FIG. 4 may be an example of the apparatus 100 of FIG. 1A to FIG. ID and the apparatus 200 of FIG. 2. According to various embodiments, the apparatus 400 may, similar to the apparatus 100 of FIG. 1A to FIG. ID and the apparatus 200 of FIG. 2, be for automated adaptive additive manufacturing or automated adaptive metal additive manufacturing or automated adaptive Hybrid-Wire Arc Additive Manufacturing (H-WAAM). According to various embodiments, in the example as represented by apparatus 400 of FIG. 4, the apparatus 400 may, similar to the apparatus 100 of FIG. 1A to FIG. ID and the apparatus 200 of FIG. 2, include the platform 110 (or table), the material deposition module 120, the sensor arrangement 130, the subtractive machining module 140, the robotic arrangement 250, and the processor 260. [00066] According to various embodiments, in the example as represented by apparatus 400 of FIG. 4, the material deposition module 120 of the apparatus 400 may be in the form of a wire arc additive manufacturing module including a welding system or machine 420 (FRONIUS TPS 400i) and a welding torch 422 (FRONIUS WF 25i ROBACTA DRIVE). Accordingly, the deposition head 122 of the material deposition module 120 of the apparatus 400 may include a welding torch and a wire feeder. According to various embodiments, in the example represented by apparatus 400 of FIG. 4, the sensor arrangement 130 of the apparatus 400 may include at least one laser sensor in the form of a 2D laser scanner 432 (MICRO-EPSILON SCANCONTROL 2910-100). According to various embodiments, in the example represented by apparatus 400 of FIG. 4, the subtractive machining module 140 of the apparatus 400 may include a milling assembly 440 or milling module or milling head assembly (PROXXON FF500). Further, according to various embodiments, the external robotic arrangement 250 of the apparatus 400 may include the first robot 252 and the second robot 254. According to various embodiments, in the example as represented by apparatus 400 of FIG. 4, the first robot 252 of the apparatus 400 may include a robot manipulator 452 or a serial manipulator (ABB IRB 1660ID), and the second robot 254 of the apparatus 400 may include a gantry robot 454 (or a Cartesian robot) made up of three linear rails (PMI KM4510) and three servos (SMARTMOTOR SM34165DT). According to various embodiments, in the example represented by apparatus 400 of FIG. 4, the processor 260 may be in the form of a central master computer which is connected to the rest of the hardware components through either an Ethernet or an RS232 communication interface. According to various embodiments, all of the control commands to the apparatus 400 may be formulated and dispatched by the central master computer (i.e. the processor 260). [00067] FIG. 5 shows a workflow diagram 500 for the apparatus 400 of FIG. 4 according to various embodiments. As shown, at 501, the only input required may be the 3D CAD model of the part (or 3D object). The CAD model may be first sliced into layers (or a plurality of image layers) with a resolution (or vertical resolution) depending on the accuracy required, and the print path (or deposition path) for each layer may be generated and stored in a library of the part layers at 503. The automated workflow may start (at 505) with the robot manipulator 452 printing or depositing the first layer at 507. When the print job is done, the gantry robot 454 may move the 2D laser sensor to scan and reconstruct the 3D surface of the printed layer at 509, and the maximum and minimum heights of the layer may be obtained. Based on the surface roughness, it may then be decided at 511 whether face milling may be required to improve the flatness of the surface. With or without milling, the final height of the current layer may then be fed into the system (or apparatus 400) at 513 and the corresponding print path (or deposition path) for that particular layer height may be extracted from the library of the part layers 503. The robot manipulator 452 then carries out the subsequent layer’s print job on top of the previous layer, and the workflow repeats until the last layer has been reached at 517.

[00068] According to various embodiments the apparatus 400 may include the platform 110 (or table) having the surface 112 on which the 3D object is to be constructed. The apparatus 400 may include the material deposition 120 module having the deposition head 122 for depositing a material. The deposition head 122 may be movable relative to the surface 112 of the platform 110 along the deposition path to deposit a layer of the material at a layer height from the surface 122 of the platform 120. The deposition path may be based on a shape generated from a layer image of the CAD model of the 3D object sliced at the layer height from the base of the CAD model. The apparatus 400 may include the sensor arrangement 130 disposed to scan and map a surface of the deposited layer of the material. The apparatus 400 may include the subtractive machining module 140 having the machining tool 142. The machining tool 142 may be movable relative to the surface 112 of the platform 110 to machine the surface of the deposited layer of the material based on comparing a surface roughness of the surface of the deposited layer of the material mapped by the sensor arrangement against a pre-set surface flatness tolerance. According to various embodiments, the material deposition module may set a subsequent layer height for depositing a subsequent layer of the material based on a finished height of the deposited layer of the material from the surface 112 of the platform 110. [00069] According to various embodiments, the apparatus 400 may further include the robotic arrangement 250. The robotic arrangement 250 of the apparatus 400 may include the first robot 252 and the second robot 254. According to various embodiments, an end- effector of the first robot 252 of the apparatus 400 may include the deposition head 122 of the material deposition module 120 and an end-effector of the second robot 254 of the apparatus 400 may include the machining tool 142 of the subtractive machining module 140. According to various embodiments, the first robot 252 of the apparatus 400 may include the robot manipulator 452 (or serial manipulator) and the second robot 254 of the apparatus 400 may include the Cartesian robot (e.g. the gantry robot 454).

[00070] According to various embodiments, the sensor arrangement 130 of the apparatus 400 may be movable scan and map the surface of the deposited layer of the material. According to various embodiments, the sensor arrangement 130 of the apparatus 400 may be mounted to the second robot 254. According to various embodiments, the sensor arrangement 130 of the apparatus 400 may include at least one laser scanner 432.

[00071] According to various embodiments, the material deposition module 120 of the apparatus 400 may include the wire arc additive manufacturing module in the form of the welding system or machine 420. According to various embodiments, the deposition head 122 the material deposition module 120 of the apparatus 400 may include the welding torch 422 and the wire feeder.

[00072] According to various embodiments, the subtractive machining module 140 of the apparatus 400 may include the milling assembly 440 (or milling module). According to various embodiments, the machining tool 142 of the subtractive machining module 140 of the apparatus 400 may include the milling tool.

[00073] According to various embodiments, the processor 260 of the apparatus 400 may be configured to control the movement of the deposition head 120 in the form of the welding torch 420 relative to the surface 112 of the platform 110 to deposit the layer of the material, to control the operation of the sensor arrangement 130 in the form of the laser scanner 432 to scan and map the deposited layer of the material including to control of the movement of the sensor arrangement 130 relative to the surface 112 of the platform 110 for scanning and mapping, and to control the movement of the machining tool 142 in the form of the milling tool relative to the surface 112 of the platform 110 to machine the surface of the deposited layer of the material. [00074] According to various embodiments, the processor 260 of the apparatus 400 may be configured to control the first robot 252 in the form of the robot manipulator 452 (or serial manipulator) to move the deposition head 120 in the form of the welding torch 420. According to various embodiments, the processor 260 of the apparatus 400 may be configured to control the second robot 254 in the form of the Cartesian robot (e.g. the gantry robot 454) to move the machining tool 142 in the form of the milling tool. According to various embodiments, the processor 260 of the apparatus 400 may be configured to control the second robot 254 in the form of the Cartesian robot (e.g. the gantry robot 454) to move the sensor arrangement 130 in the form of the laser scanner 432.

[00075] According to various embodiments, to automate the apparatus 400 of FIG. 4 comprising the various hardware and operations, a universal framework may be employed. The individual functional module, namely the additive (or deposition), registrative (or scanning) and subtractive (or machining) unit, may understand what each other is doing with very little preparation and intervention from human. The following discuss the universal strategies used in the apparatus 400 of FIG. 4 with only the CAD model of the part (or 3D object) as the input, which is general enough to be used for printing or constructing or building any part’s shape (or 3D shape). The main automated adaptive function is also described.

[00076] In the following, a unified path generation for the apparatus 400 is described. [00077] According to various embodiments, the jobs for the additive (or deposition), registrative (or scanning) and subtractive (or machining) functions may be generated solely from the CAD model, so that very little pre-processing and prior preparation by human is required. According to various embodiments, the three different paths may be generated automatically from the sliced CAD model: the additive path (or deposition path), the registrative path (or scanning path) and the subtractive path (machining path).

[00078] According to various embodiments, the additive path (or deposition path) may basically be a typical print pattern employed in additive manufacturing, and it may take any deposition patterns depending on the needs. The most common hatching patterns may be spiral (contour-based) and raster (zig-zag) patterns. The layer may be hatched into the print path (or deposition path) with a stepover distance specific to the material being deposited. [00079] According to various embodiments, for the registrative (or scanning) function, it may be advantageous for the laser sensor to know the shape of the layer that was just printed or built or constructed by the additive module (or material deposition module) so that it may not have to scan the whole workspace and thus saves on the operational time. Accordingly, unidirectional raster lines may be generated from the sliced CAD model with the required resolution of the 3D scan output as the stepover distance. These raster lines may represent the positions of the 2D laser line across the layer’s shape and form the registrative path (or scanning path) automatically generated from the CAD model of the part (or 3D object). More details on how the path may be used for the sensing and adaptive function will be discussed later.

[00080] According to various embodiments, similar to the additive (or deposition) function, the subtractive (or machining) task may also be performed on the layer surface either in a spiral or raster manner. Hence, to construct the subtractive path (or machining path) automatically, spiral or raster pattern may likewise be generated from the sliced CAD model, but now with the diameter (full or around 80%) of the face or end mill tool as the stepover distance. This path may then become the route that has to be taken by the subtractive module (or machining module) to mill and flatten the layer surface according to its shape.

[00081] According to various embodiments, to achieve the above unified path generation for the three functions of the apparatus 400 of FIG. 4, the processor 260 may take in and process the sliced CAD model of the part (or 3D object) to be printed or built or constructed. For example, a hatching software tool may be run by the processor 260 to generate the paths respectively. FIG. 6 shows examples of the three different paths for the additive 682 (deposition), registrative 684 (scanning) and subtractive 686 (machining) functions generated by the processor 260 running the software for manufacturing a test coupon part. The three different paths may be the results of the unified path generation from the sliced CAD model by the apparatus of FIG. 4. The additive path may represent the deposition path of the part layer (or 3D object layer) hatched with a stepover distance specific to the material characteristics. The registrative path may represent the positions for the 2D line laser sensor 432 hatched from the part layer (or 3D object layer) with the required scan resolution as the stepover distance. The subtractive path may represent the route to be taken by a miller (or the machining tool 142) hatched from the part layer (or 3D object layer) with a stepover distance related to a diameter of a face or end mill tool.

[00082] According to various embodiments, the processor 260 of the apparatus 400 may be configured to generate each of the deposition path for moving the deposition head 122 of the material deposition module 120 of the apparatus 400 (in the form of the welding torch 422), the scanning path for moving the sensor arrangement 130 of the apparatus 400 (in the form of the laser scanner 432), and the machining path for moving the machining tool 142 of the subtractive machining module 140 of the apparatus (in the form of the milling tool) based on the shape generated from the layer image of the CAD model of the 3D object sliced at the layer height.

[00083] In the following, the coordinate systems for the apparatus 400 are described. [00084] With the unified paths for the three adaptive functions, i.e. additive (deposition), registrative (scanning) and subtractive (machining) functions, of the apparatus 400 automatically generated from the CAD model by the processor 260, the various hardware components of the apparatus 400 may need to know the actual position of the actual part (or 3D object) to be printed or built or constructed relative to each of them so that they may move to the correct location to deposit, scan or mill the actual part (or 3D object). FIG. 7 shows the coordinate systems 780 of the apparatus 400 according to various embodiments. According to various embodiments, the positions of the coordinate frames of the components have to be calibrated relative to one another.

[00085] The coordinates of the generated unified paths may be positioned relative to the table frame T (or the coordinate frame of the platform 110) on which the actual part (or 3D object) is going to be printed or built or constructed. Hence, the coordinates of the unified paths may be generally notated as T Pm with k = {a, r, 5} for additive (or deposition), registrative (or scanning) and subtractive (or machining) paths respectively, and P is in the format of [x, y, z] coordinates. To formulate the motions of the robot manipulator as well as the gantry robot to perform the deposit, scan and mill operations based on the generated unified paths, the coordinates of the paths need to be expressed relative to the additive, registrative and subtractive tool frames (or the coordinate frame of the deposition head 122, the coordinate frame of the sensor arrangement 130, and the coordinate frame of the machining tool 142) respectively.

[00086] From the coordinate systems, the motion of the first robot 252 in the form of the robot manipulator 452 (or serial manipulator) to perform the additive (or deposition) function may be obtained from

A P Ua = T P Ua + M P T - M P A (1) where M PT and M PA are the calibrated positions of the table frame (or the coordinate frame of the platform 110) and the additive tool frame (or the coordinate frame of the deposition head 122) respectively relative to the robot manipulator frame (or the coordinate frame of the first robot 252.

[00087] The motion of the second robot 254 in the form of the gantry robot 454 to carry out the registrative (or scanning) task may be formulated as

R Pur T P Ur_new + M P T M P G - G P R (2) where M P G is the calibrated position of the gantry robot frame (or the coordinate frame of the second robot 254) relative to the manipulator frame (or the coordinate frame of the first robot 252), G PR is the calibrated position of the registrative tool frame (or the coordinate frame of the sensor arrangement 130) relative to the gantry robot frame (or the coordinate frame of the second robot 254), and T Pu r-new may be the new registrative path (or scanning path) after being processed further, which is discussed later.

[00088] The movement of the second robot 254 in the form of the gantry robot 454 to execute the subtractive (or machining) operation may be obtained as sPus = T Pus + M PT - M PG G Ps (3) where G Ps is the calibrated position of the subtractive tool frame (or the coordinate frame of the machining tool 142) relative to the gantry robot frame (or the coordinate frame of the second robot 254).

[00089] According to various embodiments, with these coordinate systems and unified paths, the whole process of the apparatus 400 may be fully automated from only the CAD model of the part (or 3D object) to be printed or built or constructed.

[00090] According to various embodiments, the processor 260 of the apparatus 400 may be configured to generate the deposition path in a coordinate frame of the deposition head 122 (e.g. A Pu a ) from the deposition path in the coordinate frame of the platform 110 (e.g. T Pu a ) generated from the layer image of the CAD model of the 3D object, a position of the platform 110 in the coordinate frame of the first robot 252 (or a calibrated position of the platform 110 relative to the coordinate frame of the first robot 252, e.g. M PT), and a position of the deposition head 122 in the coordinate frame of the first robot 252 (or a calibrated position of the coordinate frame of the deposition head 122 relative to the coordinate frame of the first robot 252, e.g. M PA)

[00091] According to various embodiments, the processor 260 of the apparatus 400 may be configured to generate the scanning path of the sensor arrangement 130 in the coordinate frame of the sensor arrangement 130 (e.g. R Pu r ) based on the scanning path in the coordinate frame of the platform 110 (e.g. T Pu r-new ) generated from the layer image of the CAD model of the 3D object, a position of the platform 110 in the coordinate frame of the first robot 252 (or a calibrated position of the platform 110 relative to the coordinate frame of the first robot 252, e.g. M P T ), a position of the second robot 254 in the coordinate frame of the first robot 252 (or a calibrated position of the coordinate frame of the second robot 254 relative to the coordinate frame of the first robot 252, e.g. M P G ) and a position of the sensor arrangement in a coordinate frame of the second robot (or a calibrated position of the coordinate frame of the sensor arrangement 130 relative to the coordinate frame of the second robot 254, e.g. G PR )·

[00092] According to various embodiments, the processor 260 of the apparatus 400 may be configured to generate the machining path of the machining tool 142 in the coordinate frame of the machining tool 142 (e.g. s Pu s ) from the machining path in the coordinate frame of the platform 110 (e.g. T Pu s ) generated from the layer image of the CAD model of the 3D object, a position of the platform 110 in the coordinate frame of the first robot 252 (or a calibrated position of the platform 110 relative to the coordinate frame of the first robot 252, e.g. M P T ), a position of the second robot 254 in the coordinate frame of the first robot 252 (or a calibrated position of the coordinate frame of the second robot 254 relative to the coordinate frame of the first robot 252, e.g. M P G ), and a position of the machining tool 142 in the coordinate frame of the second robot 254 (or a calibrated position of the coordinate frame of the machining tool 142 relative to the coordinate frame of the second robot 254, e.g. G Ps).

[00093] In the following, the sensing and adaptive function for the apparatus 400 are described.

[00094] As previously described, the registrative path (or scanning path), r P tf r, generated from the CAD model has to be further processed so as to derive the new registrative path (or new scanning path), T Pu r-new , in order for the apparatus 400 to automatically perform the scanning task to achieve the adaptive function. According to various embodiments, the generated registrative path (or scanning path), 7 F // , may only represent the desired positions of the 2D laser line on the layer’s surface. Accordingly, the motion of the sensor arrangement 130 in the form of the laser sensor 432 (i.e. T Pu r-new ) may need to be further formulated.

[00095] FIG. 8A shows an illustration of the path planning for the laser scanning operation derived from the registrative path (or scanning path), 7 F // , according to various embodiments. According to various embodiments, from the automatically-generated registrative path (or scanning path), 7 /^, a bounding box 891 which encloses the contour shape of the printed layer (or deposited layer of the material) may be first extracted, as depicted by the dashed box in FIG. 8A with the test coupon path as an example. From there, the width of the shape in the current printed layer (or layer width), which is equal to the width of the bounding box 891, may be obtained. According to various embodiments, the 2D laser scanner 432 may have a maximum width limit that it may measure at a single instance.

[00096] Hence, according to various embodiments, if the layer width (or the width of the bounding box) is longer than the laser width, multiple passes of the scanning for the laser scanner 432 may have to be formulated to cover the full part’s width, as depicted by the several overlapping dotted boxes 892 in FIG. 8A. According to various embodiments, the new registrative path (or new scanning path), T Pur_new, for the scan motion (solid arrows 893) may then be the center of each of the scan passes (dashed dot lines 894 in FIG. 8A). As the relative positions of the scan passes may be known, the scan output may be easily stitched together to reconstruct the layer’s surface.

[00097] According to various embodiments, the processor 260 may be configured to generate the scanning path in the coordinate frame of the platform (e.g. T Pur_new ) from the layer image of the CAD model of the 3D object by extracting the bounding box 891 enclosing an outline of the shape generated from the layer image, determining a number of pass for scanning based on a ratio of a width of the bounding box and a scanning width of the laser scanner 432 (i.e. the sensor arrangement 130), and generating the scanning path 893 (e.g. T P Ur n e w) based on determining the center 894 of each pass for scanning with respect to the width of the bounding box.

[00098] A pseudocode 888 in FIG. 8B summarizes the algorithm used to automatically formulate the laser scanning motion from the initial generated unified registrative path (or scanning path), T Pur, according to various embodiments. The T Pur_ new may then be fed into equation (2) above to generate the motion of the second robot 254 (in the form of the gantry robot 454) for the registrative (scanning) operation. According to various embodiments, the laser sensor 432 may be programmed to collect the 2D scan data at a distance interval following the stepover increment in the initial generated unified registrative path (or scanning path), T Pur- [00099] According to various embodiments, the original generated registrative path or (scanning path), T Pu r , itself may be useful again later on for processing the laser scan data to perform the automated adaptive function.

[000100] According to various embodiments, as the lines in T Pu r represent the 2D laser line strictly on the layer surface (or the surface of the deposited layer of material), the output of the 3D scanning, which may include data not belonging to the printed layer’s surface (or deposited layer’s surface) due to the contour shape of the layer, may then be cropped automatically and accordingly following the end coordinates of the lines in T Pu r - [000101] Hence, the scan data used for the adaptive function may only include those that belong to the surface of the deposited layer, as will be described in the following.

[000102] To test and demonstrate the capabilities of the apparatus 400, a 5 x 5 x 5 cm 3 block (or cube) was printed or built or constructed adaptively and each of the printed layers (or deposited layer) was automatically scanned to compare the actual and the theoretical heights of the layers. [000103] Table 1

Parameters (Unit) Value

Filler Material ER316LS i

Torch Speed (mm/s) 7

Wire Feed Rate (m/min) 3

Voltage (V) 14.8

Current (A) 100

Bead Height (mm) 2.24

Bead Width (mm) 4.1

Stepover Rate 0.67

[000104] Table 1 above summarizes the parameters used in the experiments. A total of 18 layers were printed (or built or constructed) and FIG. 9A shows the final printed block 970 (or cube). FIG. 9B shows the full output of the automated scan result 972 of one of the printed layers (or deposited layers), which is the 9 th layer (halfway to the print), while FIG. 9C shows the scan result 974 for the printed surface (or the surface of the deposited layer) only after the full scan data has been cropped automatically using the end coordinates from the lines in the generated unified registrative path (or scanning path), T Pu r . [000105] According to various embodiments, after automatically removing the unwanted scan data that do not belong to the printed layer (or deposited layer), the depth data may be fairly processed and the maximum and minimum heights of the current layer may be obtained. These values may be useful to decide accordingly whether milling (or subtractive machining or subtractive operation) may be required to increase or enhance the flatness of the top layer surface for subsequent print or deposition. FIG. 9D shows a sample 976 of a layer that was automatically milled (or machined) using the generated unified subtractive path (or machining path), ¾.

[000106] As each of the printed layers (or deposited layers) was automatically scanned, the actual height of the layers may be compared with the theoretical values. FIG. 9E shows the plot of the actual average height 978 of each of the printed layers (or deposited layers) compared with the theoretical expected height 979, which is the layer number times the height of the first layer. As can be seen, the actual layer height increasingly deviates from the expected height as the layer progresses upwards. The thickness of the individual layer has decreased as more layers were added. Such deviation in actual height vs expected height may cause the additive manufacturing process to have stopped prematurely at a certain layer when the gap between the actual and the expected (set) height is large enough to impede the arc establishment between the welding electrode tip and the layer’s top surface. However, the adaptive function of the various embodiments may prevent or avoid such premature stoppages.

[000107] According to various embodiments, the apparatus 400 may measure the actual layer’s height and update it on the fly to ensure the continuation and completion of the print or additive manufacturing process.

[000108] Various embodiments have provided a universal framework for an automated adaptive additive manufacturing apparatus/system and method (e.g. an automated adaptive Hybrid-Wire Arc Additive Manufacturing (H-WAAM) system). In various embodiments, the only input required to the apparatus/system and method is the CAD model of the part (or 3D object) to be built or constructed or printed. In the various embodiments, the apparatus/system and method may be able to automatically sense and adapt to the variation of the print or built or construct behavior to ensure the continuation and completion of the additive manufacturing task. In the various embodiments, the apparatus/system and method may be able to measure the current print/build/construct height after each layer’s print, decide whether subtractive (or machining) operation is required to improve the smoothness of the top surface and perform accordingly, and finally update the actual height for the subsequent layer’s print to obtain a more accurate printed or built or constructed part (or 3D object). Various embodiments may be general enough for printing or building or constructing any part’s shape (or 3D shape) as it only requires the CAD model of the part (or 3D object) as the input.

[000109] While the invention has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes, modification, variation in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims. The scope of the invention is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.