Publication: 3D printer system design and development
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Date
2019-06-01
Authors
Fan, Jian Rong
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Abstract
The advent of 3D printing has revolutionized the traditional subtractive manufacturing and being recognized as additive manufacturing where materials are added, joined or fused together successively layer by layer. However, due to open loop condition in 3D printer motion system, this may lead to layer shifting problem and result in failures and wastage of plastic. Therefore, this project aims to design a closed loop system in the stepper motion to rectify the layer shifting problem during printing. Therefore, a 3D printer is constructed with the help of Solidworks to design an innovative foldable mechanism to the printer structure as well as the installation of AVAGO incremental optical linear encoder on the XY gantry. The detection of input step and direction signal from firmware is conducted with the help of Arduino libraries, same goes to the detection of distance from linear encoder. A motor controller is designed using Arduino UNO as the control unit to receive the input signal from 3D printer firmware and generate output to the A4988 stepper motor driver to run the motor, where the response is monitored by linear encoder as the feedback for the closed loop system using bilinear transformation in order to interface with the Arduino microcontroller. The prototype of portable 3D printer is assembled and has proved to be working for its folding mechanism. The phase lead controller is being analyzed for its performance in terms of feedback of linear encoder, stability of the system, and accuracy of the controller. The linear encoder shows a dropping accuracy for longer distance in open loop system. This is due to its lower resolution compared to microstepping stepper motor. In terms of stability, a gain of K=0.25 is applied to the phase lead controller to obtain a stable response without oscillation. High accuracy is obtained for the phase lead controller and is maintained at average of 96.26% for X axis and 97.23% for Y axis. The print head is deliberately perturbed by an external force during the printing task to evaluate the designed controller performance in disturbance rejection. The system manages to rectify the error and shift back to the required position, showing the success of closed loop system in stepper motion to recover from layer shifting problem. All the objectives have been achieved.