Automation of Robotic Concrete Printing Using Feedback Control System

Abstract

-In recent years, digital fabrication is termed as "third industrial revolution" and its interaction with extrusion based cementitious material has been well known as concrete printing. In concrete printing, a gantry/robotic system deposits concrete layer by layer following G-codes generated from slicing of the 3D component. However, the robotic system does not consider the material (concrete) properties and component geometry which sometimes cause failure in the printing process. Concrete properties are usually attributed with time and therefore the system parameters such as extruder velocity and layer height are necessarily to be controlled accordingly to obtain an uninterrupted smooth flow. In line with this, our current research aims to automate the printing process by collecting material's fresh properties through a feedforward control system. A six-axis industrial Denso® robot was used for 3D printing of geopolymer concrete with the help of screw pump and ten-millimeter circular extruder. The obtained experimental results confirmed the validity and robustness of this automated set up.

Improving flexural characteristics of 3D printed geopolymer composites with in-process steel cable reinforcement

“…A four axis gantry printer (Fig. 2) was used to print eight straight walls of dimension 1000x30x39mm, with varying cable reinforcement (C10, C15 and C20) 1 Since geopolymer binder has higher stiffening rate than normal concrete (OPC), its open window for printing is also much shorter [22]. The time gap between mixing and printing has been reported to contribute towards the tensile strength of 3D printed element, especially when pulled in the layer build up direction, owing to an improved bond strength in the 3D printed interface layer when print time was kept to a minimum in both geopolymer [23] and high strength cementitious material [4].…”

Automation in the Construction of a 3D-Printed Concrete Wall with the Use of a Lintel Gripper

“…The rotary motion of the screw feeder can also be blamed for the reduced extrudability and discontinuations in the deposited layer. The problem can be solved by applying a monitoring system for rheological properties shown e.g., in [44,45]. The automatic system determines the properties of fresh mix in real time and adjusts the flow rate and printing speed within the feedback system.…”

“…The pumping installation can be upgraded with monitoring system for determination of real time rheological properties. The data can be used to e.g., steer the pumping and printing speed to produce a path of assumed dimensions [44,45].…”

Using Computer Vision for Monitoring the Quality of 3D-Printed Concrete Structures

“…Studies have tried to measure the mix workability while printing is taking place to use it as feedback to control the printing process. However, the measurement of workability in these studies is quantified indirectly by measuring shear stress and yield stress of the mix based on physical measurement devices, such as rheometers [11]; these measurements are difficult to obtain in real time.…”