DESC:FIELD OF INVENTION
This invention relates to the field of large-scale additive manufacturing. More particularly to the fabrication of structures that exceed the build volume of conventional construction 3D printing equipment with low precision set-ups.

BACKGROUND OF THE INVENTION
3D printing technology is well suited for onsite conditions, the space around the construction site is typically enough only for the building. Common 3D printers, such as the gantry printers, have a very large foot area which is a clear disadvantage for construction operations in constricted zones.
Present Technologies in the field-of-invention & their limitation(s):

Laser Tracker: It has moving components and requires regular, precise alignment and calibration. It is a relatively delicate instrument and must be set up on firm ground when used on a construction site. It is a highly sophisticated system with complex working mechanisms and not economical for construction as the machine is expensive. Light or Photo-based sensors are susceptible to the noise generated in ambience such as sunlight, rain, snow, dust, and smoke/fog.

Problem/Limitation in the present technology addressed by subject innovation: Though 3D printing technology is well suited for onsite conditions, the space around the construction site is typically enough only for the building. Common 3D printers, such as the gantry printers, have a very large foot area which is a clear disadvantage for construction operations in constricted zones. Hence, a new printer configuration is necessary that can cover a substantially large area of workspace with a minimal machine footprint. However, such machines are very susceptible to harsh environmental factors such as wind and tend to have low precision due to very little ground support. Large machines tend to have more manufacturing errors.

On-site 3D printing of structures requires large-scale machines. While these machines are durable for the rough environmental conditions at the site of construction, they are not capable of precise movement required for 3D printing construction. In order to have controlled movements of end effectors of long-range machines such as boom cranes, mobile sensors have been incorporated in the machine. However, the position and orientation of the target can often be misread when minimum number of targets are used. On the other hand, having numerous targets for proper triangulation may not be possible in many site conditions. Errors may also occur due to lapse in the feedback system between target and sensor.

Hence, there is a necessity for a new printer configuration that can cover a substantially large area of workspace with minimal machine footprint. However, such machines are very susceptible to the harsh environmental factors such as wind and tend to have low precision due to very little ground support and large machines tend to have more manufacturing errors.

The patent US11441899B2 emphasised the use of camera based tracking in all their claims. Though we are trying to achieve similar tracking of position/orientation, our system is significantly cheaper and utilises less complex equipment. The method uses ‘targets’ to get real time positional data which involves a dense flow of data from sensors to processors. This creates a risk of high resonance and lag in the system and requires mandatory tuning of all sensors in place after every setup. Our system, on the other hand, uses an LIDAR/Depth camera/IR sensor which scans the position of the template in real-time.

The patent EP3167342B1 relates the use of line follower technology for autonomous vehicles by means of creating virtual tag and instruction of translocation. This patent specifies the use of but not limited to IR sensors to assist the movement of robots whereas in our present invention, LIDAR/Depth camera/IR sensors are used to scan a template and obtain positional data.

The present subject invention overcomes the above-mentioned limitations in the system by a process/method of 3D printing which specifically caters to large-scale systems using low precision actuators. With the help of robotics and long actuators, it is possible to 3D print with appropriate level of precision.

OBJECTIVE OF THE INVENTION
The primary objective of this invention is to create a cost-effective, real-time position and orientation tracking system designed to precisely control the movement of the HP (High Precision) actuator on large-scale machines (LP actuator) used in construction 3D printing.
Another objective of this invention is that the solution is intended to be economically viable, making it accessible for large-scale construction projects while reducing the costs typically associated with high-precision tracking technologies.

Another objective of our present invention is to provide consistent, real-time feedback, allowing for adjustments and ensuring smooth and precise operations, even on large, complex structures in the construction environment.

SUMMARY OF THE INVENTION
The following summary is provided to facilitate a clear understanding of the new features in the disclosed embodiment and it is not intended to be a full, detailed description. A detailed description of all the aspects of the disclosed invention can be understood by reviewing the full specification, the drawing and the claims and the abstract, as a whole.

The present invention relates generally to full building, large scale 3D printing and, more particularly, to producing high speed construction methods and apparatus for the construction industry with low precision systems.
The present invention incorporates the following subsystems working in tandem to achieve large-scale 3D printing:
? Long boom crane system
? End effector tool compensation system
? Scanning system
? Material Depositing System (Print Head)

This system aims to ensure accurate and reliable tracking of both position and orientation, is crucial for maintaining precision during the additive manufacturing process. By optimizing the movement of the HP (High Precision) actuator, the system enhances the quality and structural integrity of the printed elements.

BRIEF DESCRIPTION OF THE DRAWINGS
The manner in which the present invention is formulated is given a more particular description below, briefly summarized above, may be had by reference to the components, some of which is illustrated in the appended drawing It is to be noted; however, that the appended drawing illustrates only typical embodiments of this invention and are therefore should not be considered limiting of its scope, for the system may admit to other equally effective embodiments.

Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements and features.

The features and advantages of the present invention will become more apparent from the following detailed description along with the accompanying figures, which forms a part of this application and in which:

Fig 1: Block Diagram describing the components of our method and system for large-scale 3d printing with low precision in accordance with our present invention;
Fig 2: Block Diagram describing the actual working of our method and system for large-scale 3d printing with low precision in accordance with our present invention;
Fig 3: Diagram describing the link arm connection, rotational axes and planar movement of the High Precision Actuator, along with the printhead, in accordance with our present invention;
Fig 4: Diagram describing the printhead, in accordance with our present invention;
Fig 5: Diagram describing the long boom crane system formed by secondary linkages connected by pin joints, in accordance with our present invention;

REFERENCE NUMERALS
100 - LP (Low Precision) Actuator (>3 DOF (Degrees of Freedom))
101 - End Effector - minimum 3 DOF and can also be more than 3 DOF
102 - Print Head
103 - Controller
104 - 3D Printed Layers
105, 106 -rigid
200 - Large Scale Actuator
201 - 3D Printed Structure
202 - End Compensation tool
203 - Printhead
204 - Template
400 – Inlet hose
401 – R motor
402 – C sensor
403 – nozzle
404 – 3D Printed layer
405 – Detection zone
406 – N layer
407 – N-1 Layer

DETAILED DESCRIPTION OF THE INVENTION
The principles of operation, design configurations and evaluation values in these non-limiting examples can be varied and are merely cited to illustrate at least one embodiment of the invention, without limiting the scope thereof.

The embodiments disclosed herein can be expressed in different forms and should not be considered as limited to the listed embodiments in the disclosed invention. The various embodiments outlined in the subsequent sections are constructed such that it provides a complete and a thorough understanding of the disclosed invention, by clearly describing the scope of the invention, for those skilled in the art.

Throughout this specification various indications have been given as to preferred and alternative embodiments of the invention. It should be understood that it is the appended claims, including all equivalents, which are intended to define the spirit and scope of this invention.

While large actuators can be used to 3D print, the poor positional accuracy and lack of close tolerance control of such large equipment limits its usage. The present invention is a special robotic arm manipulator which works with a minimum of 3 axes control as described by figure 1 and figure 2 and provides a compensation mechanism for the lack of precision in the large-scale actuator.

Figure 1 shows how the controller (103) controls the LP (Low Precision) Actuator (100) and the Effector (101), which in turn operate the printhead (102) resulting in 3D printed layers (104). The rigid (105, 106) process flow between the actuator and the effector results in accuracy and better control.

Figure 2 displays the actual construction method followed in accordance with one embodiment of our present invention. The large actuator (200) operates the robotic arm fitted with the end compensation tool (202) which has the printhead (203) attached to it at one end. The 3D printed layers (104) are printed by following the template (204).

With the help of a sensor, the position of the tool tip performing the 3D printing function will be measured; thereby aiding in finer motion of the machine. The boundary data of the structure which is to be printed is also fed via a closed loop system to the machine as a set of instructions which is not limited to G-codes. (G-code, or geometric code, is a programming language used to control computer numerical control (CNC) machines. It is used in a variety of applications, including 3D printing, CNC mills, and CNC lathes).

A sensor scans the template (204) of the base layer, placed in the appropriate position, before starting the 3D printing process. This has limited similarity to line following technology as the template is the detectable line drawn and our 3D printer acts as the follower robot. The printhead (203) follows (traces) the required position as guided by the sensor feedback and prints the layer.
The sensor reads the position of the tooltip of the printer in real-time by scanning the template (204) with respect to the base layer. This sensor in discussion which can be but not limited to IR sensors, Depth Cameras, LIDAR sensors, scans the template which is in readable format.

The large scale actuator (100, 200) and end effector (101) work in tandem to follow the path laid out by the template (204) with the guidance of the sensors. It enables us to capture the positional errors in real time and the correction measure is generated simultaneously.

This correction measure is sent to the high speed and high precision end effector which keeps the entire system within the preset limits of errors allowed in the system. Thus, the 3D printed layers have the desired dimensional accuracy and quality.

By this method, the error in our large scale system is continuously corrected by our high precision end effector (202,101) and the 3D printed layers (201) are always accurate as per the structure’s positional data.

The present invention has developed a cost-effective real time position and orientation tracking system for precise movement of end effector of large machines in construction 3D printing. The main components of our system are given below and explained in detail in the later passages:

End Effector (101, 202) : the tool fixed at the end of a manipulator arm (robotic arm) that can do designated functions in complete synchronisation with the motion of the robot.
Low Precision (LP) Actuator (100, 200): a machine that is composed of numerous joints with varying degrees of freedom and whose Tool Position can be manipulated by manipulating its joints.
Printhead (Material Delivery System) (203): This is the material delivery and control system that enables deposition of layers.
Datum (204): The first layer of the structure’s model data needs to be converted into a readable format for the sensor to scan it. Hence, the base layer after slicing is made into a physical template which can be transported and fixed to any location where the printing is desired.
Control Systems (103): It performs the computation using the feedback of the sensor and sends commands to End Effector to do compensation. It also sends commands to LP (Low Precision) Actuator to do the printing operations.
Sensor System: The major sensors in this system are, but not limited to, tracking sensors such as infrared, line width measurement and positional sensors. In addition, we also use various sensors such as but not limited to limit switches and distance measuring sensors (to accurately measure the global position of the tool attached to the large-scale printer).

The components of one embodiment of our present invention are given in detail below:

End Effector or High Precision actuator
It is the tool fixed at the very end of a manipulator arm (robotic arm) that can do designated functions in complete synchronisation with the motion of the robot itself. In our subject invention, the end effector consists of a minimum 3-DOF which can also be more which enables us to move our printhead in X, Y & Z coordinates, thereby allowing the positional compensation of Printhead/Nozzle.

Low Precision Actuator
Low Precision Actuator is a machine that is composed of numerous joints with varying degrees of freedom and whose Tool Position can be manipulated by manipulating its joints. While both end effector and main actuator are kinematic manipulators capable of manipulating their respective tool positions, the difference is the former is a small-scale system with high precision whereas the latter (boom crane) is a large-scale system with low precision. The LP (Low Precision) Actuator
can be but not limited to hydraulic cylinders, cable driven, or electric motors.
Sensor System
The major sensors in this system are the tracking sensors such as infrared and positional sensors. In addition, we also use various sensors such as limit switches and distance measuring sensors (to accurately measure the global position of the tool attached to the large-scale printer) are also present.
Scanning system
The scanning system includes but is not limited to the following:
1. Template: which could be but not limited to physical groove, acrylic/sheet metal cutout or tape/paint marked on the ground level on any desired location.
2. Colour detection sensor: which could be a camera, optical sensor, and so on
3. Depth detection sensor: which could be a camera, LIDAR, optical sensor and so on.
4. Edge detection sensor: which could be a camera, LIDAR, optical sensor and so on.
5. Processor module: converts raw data captured by the various sensors into usable information based on preexisting techniques such as but not limited to edge detection, image processing, machine vision, depth plot and so on.

The scanning system gathers the necessary information from the environment based on the template or the 3D-printed layers and this information is processed and transferred as input to the controller which in turn can manipulate the HP (High Precision) and LP (Low Precision) actuator to ensure the layer accuracy is retained. Large-scale construction machines have neither built-in information on the start position for printing nor the bounding limits of the structure to be constructed. To calibrate the machine for a structure, a physical template is required. This template will be similar in design to the first layer of the structure, made in a readable format for the corresponding sensor used. Since we are using a combination of cameras for depth and colour information, the physical template can be but is not limited to Infra-Red detectable markings, acrylic or sheet metal cutouts embossed from the ground level, groove cut on the floor such that it debossed from the ground level and so on.

Template
The first layer of the structure’s model data needs to be converted into a readable format for the sensor to scan it. Hence, the base layer after slicing is made into a physical template that can be transported and fixed to any location where the printing is desired.

The main idea of the template is to make it detectable for the sensors mentioned previously, hence it could be anything that stands out from the background, the more contrast we can give to the template the better it can be detected by the sensors.

One of the few ways of achieving this would be using an acrylic/sheet metal cutout that will be an exact geometrical replica of the 1st layer and this can be positioned at any desired location where we will be starting the 3D printing process. We can also simply use tape/paint to draw out the first layer on the ground level, but this would be slightly less accurate than using a laser-cut acrylic template. Thirdly we can also make groove-like patterns on the ground with the help of a chisel or any machine such that this groove exactly matches the 1st layer geometrically. Finally, the template can be any physical representation of the geometry of our 1st layer which is detectable by the sensors.

Processor Module:
It performs the computation using the feedback of the sensor and sends commands to the End Effector to do compensation. It also sends commands to the LP (Low Precision) Actuator to do the printing operations.

Through the scanning system, with sensors such as but not limited to the Camera IR sensor reads the physical template, and this global space location data is stored in the machine using the GNSS module. Using this as a datum, our machine will stay within the permissible limit of geometric deviation of the given structure.

Controller
The controller acts as the system's brain, gathering and processing all relevant information to generate commands. In one scenario, the HP (High Precision) and LP (Low Precision) actuators must receive positional data to ensure precision during 3D printing. We can calculate the necessary adjustments to correct any nozzle misalignment or offset by analysing sensor data from the scanning system. This process is commonly known as inverse kinematics in robotics. Essentially, based on the target position of the actuator, we can reverse-calculate the required angles and lengths of each axis within the actuator to accurately position the nozzle.

In addition to positional accuracy, the controller also manages the synchronization of movements between different actuators, ensuring that each component works in harmony to achieve smooth and precise motion. It continually monitors feedback from the system, allowing real-time adjustments to be made if there are any deviations from the desired trajectory. This feedback loop is critical in maintaining the quality of the 3D print, as even small misalignments can affect the final product. Advanced algorithms can also be incorporated into the controller to optimize movement paths, reduce mechanical stress, and enhance overall system efficiency, further contributing to the consistency and reliability of the printing process.
Boom cranes are large-scale machines commonly used in construction. They are typically used for reaching very high points to deliver concrete slurry, and water (in case of firefighting) and they are also used for hoisting in certain models. It consists of but is not limited to hydraulic actuators that can stretch each link in the machine to tens of metres. Each joint is defined to rotate in a range that enables the positioning of the boom crane end.

A long boom crane system is a type of kinematic mechanism formed by secondary linkages which are connected by pin joints that enable the system to cover a large volume of three-dimensional space. As shown in Fig 4 and Fig 5, L1, L2, L3 and L4 are the secondary links connected with pin joints that allow each link arm to rotate about the pinned axis i.e., P1, P2, P3 and P4. This rotation about the pinned axis can be enabled by but not limited to actuators such as hydraulic pistons, linear screws and so on i.e., A1, A2, A3, and A4. Link arm L1 has an additional degree of freedom to rotate about axis O1 which is actuated by but not limited to Rack and pinion, hydraulic motor, and so on.

The printhead also called the material delivery system is rigidly connected to the HP (High Precision) system; hence HP (High Precision) system can reposition the Nozzle at any instance controlled by the motion controller, as shown in fig 4.

Printhead (Material Delivery System)
The printhead (203) comprises the following components:
? Inlet hose (400)
? R motor (401)
? C sensor (402)
? Detection zone (405)
? Nozzle (403)
The deposition of material is controlled by the printhead with the help of a nozzle (403) and inlet hose (400), material is pumped to the print head via the inlet hose (400) and with the appropriate nozzle (403) size 3D printed layers (404) can be shaped and deposited uniformly.

C sensors (402) consisting of C1 and C2 sensors are mounted adjacent to the nozzle such that they are collinear to the position of the nozzle while facially vertically down. These sensors are rotationally composed as they need to be repositioned in line with the 3D printed layers at all times, to do the scanning operations.

The R motor (401) connects the mounting of the sensor via but is not limited to a timing belt and pulleys which enables us to reposition the sensor to any orientation required. While we are printing straight lines this feature is not required but if the layers are going to curve and turn then sensors need to be dynamically repositioned at all times so we can scan the layers and get the necessary information out of them.

Sensors (402) C1 and C2 work in tandem to provide us with the most accurate information that can be gathered while 3D printing. Based on the direction of printing C1 will be scanning the ‘N-1’ layer (407) and C2 will be scanning the ‘N’ layer (406), and vice versa if the direction of 3D printing is reversed. Data such as but not limited to the layer width. Layer height, and so on can be captured from ‘N’ (406) and ‘N-1’ layers (407). Also, defects such as but not limited to layer bulges, cracks, offsets, and layer thinning can be captured dynamically with the help of C1 and C2 sensors.

Advantages of our present invention:
The major utilities/advantages/novelties of our present invention are illustrated below:
? Indefinite adaptability - The subject invention is a process/method that can be adapted to any scale of operation. Hence, the invention is not limited to existing machines or certain types of machines and applies to larger and newer forms of machinery that might be developed in the future. The idea of creating stabilization for a less accurate system opens the door for other adaptations of similar functionalities that could increase the range of machinery used for 3D printing.
? Construction in densely populated cities – Our equipment's compact size allows operations to be conducted even in areas with narrow roads and high population density, minimizing disruption to surrounding infrastructure. Its mobility further enhances its versatility, enabling rapid deployment to various locations without the need for extensive setup or transportation logistics. Additionally, we can perform off-shore construction, such as using a printer on a ship to execute projects on the ocean, like building crude oil extraction facilities or ports for coastal cities. This mobility extends to other marine-based structures, including floating platforms, renewable energy installations, or underwater tunnels, making it ideal for a wide range of urban and maritime construction projects. The equipment's ease of relocation ensures it can adapt to different environments quickly, ensuring efficiency across diverse construction sites.
? Speed of construction - Since the overall complexity of the method is fairly simple, scaling up and execution takes significantly less time.
? Economy - The prior art performs the same function as the invention in question, but it relies on highly sensitive and costly components. These expensive sensors and components make the system impractical due to the high operational and capital expenses, particularly in the construction industry. Therefore, we believe that the current invention offers a more straightforward and cost-effective alternative to these expensive tools.

Additionally, the proposed invention not only reduces costs but also simplifies maintenance and increases durability, making it more accessible for widespread adoption. Its robust design is better suited for harsh environments, which are common in construction, and minimizes the need for frequent repairs or replacements, further enhancing its feasibility and long-term value.

,CLAIMS:CLAIMS:
I/We claim:
1. A system for large-scale 3d printing with low precision with real time position and orientation tracking system for precise movement of end effector of large machines in construction 3D printing, characterized by:
a. The High Precision Actuator (202)
b. The Low Precision Actuator (200)
c. The PrintHead (203)
d. The Scanning system:
i. The Sensing system
ii. The Processor module
iii. The Template
Wherein the large actuator (200) operates the robotic arm fitted with the end compensation tool (202) which has the printhead (203) attached to it at one end. The sensing system uses the sensors placed at the actuators and required positions at the construction site to collect information;
the boundary data of the structure which is to be printed is also fed via a closed loop system to the processor module;
a sensor scans the template (204) of the base layer, placed in the appropriate position, before starting the 3D printing process;
the large scale actuator (100, 200) and end effector (101) work in tandem to follow the path laid out by the template (204) with the guidance of the sensors to capture the positional errors in real time and the processor module generates the correction measure which is sent to the Low Precision Actuator and high precision end effector keeps the entire system within the preset limits of errors allowed in the system.

2. The system for large-scale 3D printing with low precision with real time position and orientation tracking system, as claimed in claim 1, wherein the End Effector or High Precision actuator (202) is the tool fixed at the very end of a manipulator arm (robotic arm) (200) that can do designated functions in complete synchronisation with the motion of the robot itself; The end effector consists of =>3-DOF or more (3 Degrees Of Freedom) which enables us to move our printhead (203) in X, Y & Z coordinates, thereby allowing the positional compensation of Printhead/Nozzle.

3. The system for large-scale 3D printing with low precision with real time position and orientation tracking system, as claimed in claim 1, wherein the Low Precision Actuator (200) is a machine composed of numerous joints with varying degrees of freedom; It’s tool position can be manipulated by manipulating its joints and can be hydraulic cylinders, cable driven, or electric motors.

4. The system for large-scale 3D printing with low precision with real time position and orientation tracking system, as claimed in claim 1, wherein, the Sensor System includes the tracking sensors such as infrared and positional sensors as the major sensors along with limit switches and distance measuring sensors to accurately measure the global position of the tool attached to the large-scale printer.

5. The system for large-scale 3D printing with low precision with real time position and orientation tracking system, as claimed in claim 1, wherein the scanning system includes:
a. Template: A template can be any physical representation of the geometry of our 1st layer of the construction which is detectable by the sensors and could be but not limited to physical groove, acrylic/sheet metal cutout or tape/paint marked on the ground level on any desired location.
b. Colour detection sensor: which could be a camera, optical sensor, and so on
c. Depth detection sensor: which could be a camera, LIDAR (Light Detection and Ranging), optical sensor and so on.
d. Edge detection sensor: which could be a camera, LIDAR (Light Detection and Ranging), optical sensor and so on.
e. Processor module: converts raw data captured by the various sensors into usable information based on preexisting techniques such as but not limited to edge detection, image processing, machine vision, depth plot and so on.
Wherein the scanning system gathers the necessary information from the environment based on the template or the 3D-printed layers and this information is processed by the processor module and transferred as input to the controller which in turn can manipulate the HP (High Precision) and LP (Low Precision) actuator to ensure the layer accuracy is retained.

6. The system for large-scale 3D printing with low precision with real time position and orientation tracking system, as claimed in claim 1, wherein the controller, in addition to positional accuracy, manages the synchronization of movements between different actuators and continually monitors feedback from the system, allowing real-time adjustments to be made if there are any deviations from the desired trajectory.

7. The system for large-scale 3D printing with low precision with real time position and orientation tracking system, as claimed in claim 1, wherein, the printhead also called the material delivery system is rigidly connected to the HP (High Precision) system; hence HP (High Precision) system (202) can reposition the Nozzle (403) at any instance controlled by the motion controller.

8. The system for large-scale 3D printing with low precision with real time position and orientation tracking system, as claimed in claim 1, wherein, the Printhead (203) (Material Delivery System) consists of:
a. Inlet hose (400)
b. R motor (401): The R motor connects the mounting of the sensor via but is not limited to a timing belt and pulleys which enables us to reposition the sensor to any orientation required.
c. C sensor: (402) Sensors C1 and C2 work in tandem to provide the most accurate information that can be gathered while 3D printing.
i. It consists of C1 and C2 sensors mounted adjacent to the nozzle such that they are collinear to the position of the nozzle while facially vertically down;
ii. The sensors are rotationally composed as they need to be always repositioned in line with the 3D printed layers (404), to do the scanning operations.
iii. C1 will be scanning the ‘N-1’ layer (407) and C2 will be scanning the ‘N’ layer (406), and vice versa if the direction of 3D printing is reversed.
iv. Data such as the layer width, layer height, and defects such as layer bulges, cracks, offsets, and layer thinning can be captured from ‘N’ (406) and ‘N-1’ layers (407).
d. Detection zone (405)
e. Nozzle (403)
wherein the deposition of material is controlled by the printhead with the help of a nozzle (403) and inlet hose (400), material is pumped to the print head via the inlet hose and with the appropriate nozzle size 3D printed layers (404) can be shaped and deposited uniformly.