PROCEEDINGS OF UNIVERSITY OF RUSE - 2016, volume 55, book 3.1. НАУЧНИ ТРУДОВЕ НА РУСЕНСКИЯ УНИВЕРСИТЕТ - 2016, том 55, серия 3.1

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SAT-10.326-2-EEEA-06

Investigation of a closed-loop electronic system fo r control of a 3D printer

Seher Kadirova, Berran Remzi, Teodor Nenov

Изследване на електронна система с обратна връзка за управление на 3D принтер

Сехер Кадирова, Берран Ремзи, Теодор Ненов

Abstract: The purpose of the paper is to explore the improvements in speed using closed-loop control for the gantry motion in additive manufacturing machines. The authors designed and built a demonstration system to quantify the performance. Microprocessor control system for three-dimensional (3D) printers with direct current motors: 3D printing, also known as additive manufacturing (AM), refers to various processes used to synthesize a three-dimensional object. In 3D printing, successive layers of material are formed under computer control to create an object. In the widely used three-dimensional printer drive going through stepper motors which have no feedback. In order to increase resistance to external influences, reducing weight, lowering power consumption is offered traction systems by replacing stepper motors with direct-current motors which have optical encoder for position feedback. In the paper a low-cost closed-loop controller for the X and Y and Z axes has been evaluated. Flow diagram of the control system has been proposed in the article.

Key words: 3D printer, direct-current motors, position feedback, optical encoder, Arduino Mega.

INTRODUCTION The technology of 3D printing is a quite new technology. It is being developed as a

rapid prototyping process since the beginning of the century. Last years this process is moving more and more for private usage. So everybody could create virtual 3D models and is able to print them out directly. 3D printers make things by building them up, a layer at a time, from a particular material, rather than removing it by cutting, drilling or machining - which is why the process is also called additive manufacturing [1, 3] .

The aim of the paper is development and investigation of a low-cost closed-loop controller for the X, Y and Z axes of an entry-level three-dimensional (3D) printer.

DEVELOPMENT OF A CLOSED-LOOP ELECTRONIC SYSTEM FOR CONTROL OF A 3D PRINTER

To explore these opportunities, a closed-loop controller applicable to the 3D printer gantry control is developed. The controller is designed to be easily tuned and applicable to a wide variety of rapid prototyping platforms. The block diagram of the developed closed-loop electronic system is presented in fig.1.

PROCEEDINGS OF UNIVERSITY OF RUSE - 2016, volume 55, book 3.1. НАУЧНИ ТРУДОВЕ НА РУСЕНСКИЯ УНИВЕРСИТЕТ - 2016, том 55, серия 3.1

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Fig. 1 Block diagram of the electronic system

The power lines are presented by red arrows, as the communication lines are by blue arrows. The AC/DC converter 12V supplies all peripheral devices of the three-dimensional printer and is responsible to ensure the requirements of the power devices. Block "DC / DC 5V" delivers a fixed output of 5V and supplies all logical drives in the developed device. The driver for the servo motor is L298. This driver has two power lines, the one is logic supply (5V) and the other one is the power supply for control of the servo motor. The Arduino Mega block represents interpreter of the Gcode and controls all the periphery of the three-dimensional printer. It has two communication lines: the one is USB port and the other one can be configured as logical and analogue inputs/outputs. The PC transforms the required object into a three-dimensional file in Gcode and sends it to the printer via USB communication line. Two key differentiators between stepper and servo systems involve the use of a feedback device and the complexity of the amplifier electronics. Servos, by definition, are closed-loop systems utilizing a feedback device. Steppers are open-loop systems with no feedback. Servo Motors RS-385PW have been used for control of the driving part of the three-dimensional printer. The main advantage of Mabuchi RS-385PW is the encoder, which covers the accuracy requirements. A view of the developed and investigated 3D printer is presented in fig.2.

Power supply

AC/DC 12V

DC/DC

5V

Driver for a Servo motor

Arduino Mega board PC

Servo Motor Mabuchi RS-

385PW

PROCEEDINGS OF UNIVERSITY OF RUSE - 2016, volume 55, book 3.1. НАУЧНИ ТРУДОВЕ НА РУСЕНСКИЯ УНИВЕРСИТЕТ - 2016, том 55, серия 3.1

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Fig. 2 A common view of the 3D printer Printing STL is the standard file type used by most additive manufacturing systems. STL is a

triangulated representation of a 3D CAD model. Once completed, the STL file needs to be processed by a piece of software called a "slicer," which converts the model into a series of thin layers and produces a G-code file containing instructions tailored to a specific type of 3D printer. Then this G-code file can be printed (the software responsible for this charge G-code and sends instructions to the printer).

The program used for model treatment is Repetier Host. It is very flexible and has enough free pins for later extensions. It allows to follow the trail of printer’s nozzles, to see in advance the pattern to be printed, and also the available real model on the printing bed. It allows control of odds for submission of material. Another opportunity is the possibility for the user to change the G-code and printed object in a different way and for saving material for printing.

The visualization of a 3D model before and after treatment is shown in fig. 3.

Fig. 3 3D model before and after treatment

PROCEEDINGS OF UNIVERSITY OF RUSE - 2016, volume 55, book 3.1. НАУЧНИ ТРУДОВЕ НА РУСЕНСКИЯ УНИВЕРСИТЕТ - 2016, том 55, серия 3.1

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RESULTS The development of such systems plays an important role in addressing the needs of

modern manufacturing especially with the advent of high-speed machining techniques and fast, PC-based machine tool control systems that provide sufficient processing speed. Such efforts to minimise and eliminate tracking and contouring errors reflect directly on machine performance and enable the production of high precision machined components.

Table 1 presents results observed from the experimental investigation of the system. Table 1

The using of PID controller improves the productivity. The energy consumption is

reduces by 60%, printing time by 10%, the acceleration is increased by 20% with no loss of accuracy. The system successfully takes into account and correct the errors by use of the PID algorithm and as guarantees precision and precludes displacement of the coordinate system. In this research the increased productivity with the integrated hardware and software changes has been presented.

Fig. 4 Results, observed from using the algorithm of Bresenham

PROCEEDINGS OF UNIVERSITY OF RUSE - 2016, volume 55, book 3.1. НАУЧНИ ТРУДОВЕ НА РУСЕНСКИЯ УНИВЕРСИТЕТ - 2016, том 55, серия 3.1

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The red line presents the values observed from the algorithm of Bresenham, as the

accuracy is ∆=300um. The blue line reperesents the position of the printing head. CONCLUSIONS AND FUTURE WORK In this study a low-cost closed-loop controller for the X and Y and Z axes has been

developed and evaluated. Tracking and contour errors are two very important aspects that need to be effectively

addressed in order to maintain and enhance the dynamic performance of CNC machine tools. Extensive research, as analysed above, has been conducted in these two fields with the aim of arriving at new and improved methods of minimising and eliminating these errors.

The absolute error achieved from 40 measurements of the system is 0,3mm, which is lower comparing to the other similar systems.

REFERENCES [1]. Weiss, B., Storti, D., & Ganter, M. (2015). Low-cost closed-loop control of a 3D

printer gantry. Rapid Prototyping Journal, 21(5), 482-490. DOI: 10.1108/RPJ-09-2014-0108.

[2]. Ramesh, R., Mannan, M.A. and Poo, A.N. (2005), “Tracking and contour error control in CNC servo systems”, International Journal of Machine Tools and Manufacture, Vol. 45 No. 3, pp. 301-326. http://dx.doi.org/10.1016%2Fj.ijmachtools.2004.08.008

[3]. Pearce, Joshua M.; et al. (2010). "3-D Printing of Open Source Appropriate Technologies for Self-Directed Sustainable Development". Journal of Sustainable Development. 3 (4): 17–29. doi:10.5539/jsd.v3n4p17

ABOUT THE AUTHORS Assis. Prof. Seher Kadirova, PhD, University of Rousse, Department of Electronics,

Phone: +359 82 888 516, e-mail: skadirova@ecs.uni-ruse.bg. Researcher Berran Remzi MsC, University of Rousse, Department of Electronics

Phone:+359 883 493 372; e-mail: berran@abv.bg. Researcher Teodor Nenov, University of Rousse, Department of Electronics

Phone:+359 899 401 183; e-mail: tedkata26@mail.bg.