ODTÜdepartment of mechanical engineering
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NEWS

About Courses, Projects and Publications
  • August 9
    2019
    Chicago - USA

    Presentations

    ICPR 2019 - International Conference on Production Research

    Papers titled as "Embedding QR Codes on the Interior Surfaces of FFF Fabricated Parts" and "Effect of Lattice Structures on Natural Frequency of SLA Fabricated Parts" were presented at the ICPR2019.
  • June 24
    2019
    Limerick - Ireland

    Presentations

    FAIM 2019 - International Conference in Flexible Automation and Intelligent Manufacturing

    Papers titled as "A Continuous Path Planning Approach on Voronoi Diagrams for Robotics and Manufacturing Applications", "Generation of Optimized Voronoi Based Interior Structures for Improved Mechanical Properties", "Simulator of an additive and subtractive type of hybrid manufacturing system", and "Investigation of Variable Bead Widths in FFF Process" were presented at the FAIM2019.
  • May 23
    2019
    Wels - Austria

    Presentation

    REM 2019 - IEEE International Conference on Research and Education in Mechatronics

    Paper titled as "Single Axis Attitude Controller Design Using Pulse Width Modulated Thruster" was presented at the REM2019. You may view the paper from the following link.
  • March 25
    2019
    ODTÜ

    PAPER

    Materials and Manufacturing Processes

    Our paper titled as "Shrinkage compensation approach proposed for ABS material in FDM process" is available online now. You may view it from the following link.
  • March 18
    2019
    Ilmenau - Germany

    Presentation

    ICM 2019 - IEEE International Conference on Mechatronics

    Paper titled as "A Cloud Manufacturing Application for Additive Manufacturing Methods" was presented at the ICM2019. You may view the paper from the following link.
  • June 28
    2018
    ODTÜ

    PAPER

    IISE Transactions

    Our paper titled as "Generation of Patterned Indentations for Additive Manufacturing Technologies" is available online now. You may view it from the following link.
  • June 10
    2018
    Columbus - USA

    Presentations

    FAIM 2018 - International Conference in Flexible Automation and Intelligent Manufacturing

    Papers titled as "Topology optimization of 2.5D parts using the SIMP method with a variable thickness approach" and "Comprehensive Analysis of the Shrinkage Compensation Approach Proposed for the FDM process" and "Tuning the Center of Gravity of 3D Printed Artifacts" are presented at the FAIM2018.
  • May 27
    2018
    Palermo - Italy

    PAPERS

    ESAFORM2018

    Papers presented at ESAFORM2018 conferences are available online now and they are all open access.
      Utilization of curve offsets in additive manufacturing (view)
      An automated design and fabrication pipeline for improving the strength of 3D printed artifacts under tensile loading (view)
  • Nov 25
    2017
    ODTÜ

    PAPER

    Robotics and Computer-Integrated Manufacturing

    Our paper titled as "A novel command generation paradigm for production machine systems" is available online now. You may view it from the following link.
  • Nov 11
    2017
    ODTÜ

    PAPERS

    FAIM2017 & ESAFORM2017

    Papers presented at FAIM2017 and ESAFORM2017 conferences are available online now and they are all open access.
      The Role of Additive Manufacturing in the Era of Industry 4.0 (view)
      A New Method for Generating Image Projections in DLP-type 3D Printer Systems (view)
      Improving the strength of additively manufactured objects via modified interior structure (view)
  • Sep 06
    2017
    ODTÜ

    PAPER

    The International Journal of Advanced Manufacturing Technology

    My paper on shrinkage compensation in FDM process is available online now. You may view it form the following link.
  • Aug 16
    2017
    ODTÜ

    Workshop

    3D Printing and Additive Manufacturing

    I am co-organizing the workshop and will be giving series of seminars on different Additive Manufacturing methodologies. It will be held between 18 - 22 September, 2017.
  • Aug 12
    2017
    Kos Island - Greece

    Presentations

    EUSIPCO2017 Workshop on Creative Design and Advanced Manufacturing

    I will present our papers titled as "Formation of Patterned Indentations for Additive Manufacturing Applications" and "Current Trends and Research Opportunities in Hybrid Manufacturing" on September 2, 2017.
  • July 20
    2017
    Ankara - Turkey

    Project Grant

    TÜBİTAK - 1001

    Our project titled as A Smart- and Hybrid Manufacturing System Utilizing Additive Manufacturing Methods and Machining is to be funded by TÜBİTAK.
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RESUME

EDUCATION
  • 2010
    2014
    Ankara - Turkey

    MECHANICAL ENGINEERING - PHD

    ODTÜ

    Advanced Motion Command Generation Paradigms for CNC Systems
  • 2007
    2010
    Ankara - Turkey

    MECHANICAL ENGINEERING - MSc

    ODTÜ

    Design of Advanced Motion Command Generator Utilizing FPGA
  • 2003
    2007
    Ankara - Turkey

    MECHANICAL ENGINEERING - BSc

    ODTÜ

    "The undergraduate program of our department received full accreditation by Accreditation Board for Engineering and Technology, Inc. ABET."
  • 2004
    2007
    Ankara - Turkey

    MECHATRONICS - Minor

    ODTÜ

    "The main purpose of this program is to provide the successful and motivated students within broad knowledge of mechatronics that will enable them to practice their profession in an interdisciplinary manner."
ACADEMIC AND PROFESSIONAL POSITIONS
  • Since
    2015
    Ankara - Turkey

    Assistant Professor

    ODTÜ

    Teaching manufacturing and design courses and conducting research on additive manufacturing technologies
  • 2014
    2015
    Indiana - USA

    Visiting Assistant Professor

    Purdue University

    Taught CS 250 - Computer Architecture and conducted research on computational geometry and fused deposition modelling
  • 2007
    2014
    Ankara - Turkey

    RESEARCH ASSISTANT

    ODTÜ

    Assisted different courses in the mechanical engineering curriculum and conducted research on FPGAs, hydraulic systems, CNC machinery and computational geometry
HONORS AND AWARDS
  • 2017
    2020
    Ankara - Turkey

    PROJECT GRANT - Principal Investigator

    TÜBİTAK

    A Smart- and Hybrid Manufacturing System Utilizing Additive Manufacturing Methods and Machining

    The main purpose of the project is to develop a multi-axis hybrid manufacturing system that takes the advantages of traditional machining process and additive manufacturing techniques.

  • 2017
    2018
    Ankara - Turkey

    PROJECT GRANT - Principal Investigator

    TÜBİTAK

    A Novel Design and Fabrication Pipeline for 3D Printers: LIPRO

    The main aim of the project is to overcome the disadvantages of the current design and fabrication pipeline of 3D printer systems with a short pipeline and a compact command generation paradigm based on List Processors.
  • July
    2016
    Ankara - Turkey

    PROJECT GRANT - Principal Investigator

    ODTÜ - BAP

    Improving the Dimensional Accuracy of 3D Printed Artifacts
  • 2010
    2014
    Ankara - Turkey

    PhD Scholarship

    TÜBİTAK

    Advanced Motion Command Generation Paradigms for CNC Systems
  • July
    2010
    Heraklion - Crete - Greece

    BEST PAPER AWARD

    IEEE - 8th Workshop on Intelligent Solutions in Embedded Systems

    This paper focuses on a novel command generator for servo-motor drives to be used as an integral part of their motion controllers. The method, which incorporates a new data compression algorithm, is capable of generating trajectory data at variable rates. In this paradigm, higher-order differences of a given trajectory (i.e. position) are first computed and thus the resulting data are compressed via the proposed technique. The generation of the commands is carried out according to the feedrate (i.e. the speed along the trajectory) set by the external logic dynamically. The paper discusses the implementation of the method on a Field Programmable Gate Array (FPGA). During implementation Very High Speed Integrated Circuit Hardware Description Language (VHDL) is used rather than using embedded processors on the FPGA chip. The performance of the method is assessed according to the resources used in the FPGA chip on the development board and these results are also compared with the same approach without an interpolator.
  • November
    2009
    Tokyo - Japan

    CONFERENCE TRAVEL GRANT

    TÜBİTAK

    For the International Conference on Electrical Machines and Systems (ICEMS)
  • 2007
    2010
    Ankara - Turkey

    MSc Scholarship

    TÜBİTAK

    Design of Advanced Motion Command Generators Utilizing FPGA
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PUBLICATIONS

PUBLICATIONS LISTS
ALL
SORTING BY DATE
23 Nov 2017

A novel command generation paradigm for production machine systems

Robotics and Computer-Integrated Manufacturing

This paper presents a new command generation technique titled VEPRO for computer controlled production machinery. In this method, the tool trajectory is described by a high-level scripting language that enables parametric representations of complex work-piece geometries. The interpreted script is then employed to generate the interpolation data required to compute a tool trajectory that is subjected to a number of kinematic constraints. A real-time interpolator is employed to provide the position commands required by each motion controller in a synchronous fashion.
Journal Selected Ulas Yaman and Melik Dolen

A novel command generation paradigm for production machine systems

Ulas Yaman and Melik Dolen
Journal Selected
27 Jun 2017

The Role of Additive Manufacturing in the Era of Industry 4.0

Modena - Italy

The latest industrial revolution, Industry 4.0, is encouraging the integration of intelligent production systems and advanced information technologies. Additive manufacturing (AM) is considered to be an essential ingredient in this new movement. In this paper, a comprehensive review on AM technologies is presented together with both its contributions to Industry 4.0. The review focusses on three important aspects of AM: recent advances on material science, process development, and enhancements on design consideration. The main objective of the paper is to classify the current knowledge (and technological trends) on AM and to highlight its potential uses.
Conference Ugur M. Dilberoglu, Bahar Gharehpapagh, Ulas Yaman, and Melik Dolen

The Role of Additive Manufacturing in the Era of Industry 4.0

Ugur M. Dilberoglu, Bahar Gharehpapagh, Ulas Yaman, and Melik Dolen
Conference
27 Jun 2017

A new method for generating image projections in DLP-type 3D printer systems

Modena - Italy

This paper presents a novel method for generating image projections required for Digital Light Processing type 3D printer systems where the entire cross-section of the printed object is directly formed via projecting the image onto a vat of photopolymers. The cross-sections (i.e. slices), which are initially represented as bitmap images, are compressed via a novel lossless compression technique which makes good use of relative data encoding. The coherence between the consecutive slices (or images) are taken into account in this proposed paradigm. The method yields satisfactory performance in terms of data compaction achieved in the test cases considered.
Conference Ulas Yaman, Melik Dolen, Ugur M. Dilberoglu, and Bahar Gharehpapagh

A new method for generating image projections in DLP-type 3D printer systems

Ulas Yaman, Melik Dolen, Ugur M. Dilberoglu, and Bahar Gharehpapagh
Conference
26 Apr 2017

Improving the strength of additively manufactured objects via modified interior structure

Dublin - Ireland

In this study, an alternative method is proposed in which the strength of AM fabricated parts is improved employing direct slicing approach. Traditional Computer Aided Manufacturing (CAM) software of 3D printers takes only the geometry as an input in triangular mesh form (stereolithography, STL file) generated by Computer Aided Design software. This file format includes data only about the outer boundaries of the geometry. Interior of the artifacts are manufactured with homogeneous infill patterns, such as diagonal, honeycomb, linear, etc. according to the paths generated in CAM software. The developed method within this study provides a way to fabricate parts with heterogeneous infill patterns by utilizing the stress field data obtained from a Finite Element Analysis software, such as ABAQUS. According to the performed tensile tests, the strength of the test specimen is improved by about 45% compared to the conventional way of 3D printing.
Conference Can Mert Al and Ulas Yaman

Improving the strength of additively manufactured objects via modified interior structure

Can Mert Al and Ulas Yaman
Conference
06 Sep 2017

Shrinkage compensation of holes via shrinkage of interior structure in FDM process

Ankara - Turkey

An interior design methodology to compensate for the shrinkage in the holes of artifacts fabricated with desktop 3D printers employing fused deposition modeling process is presented in this study. The method utilizes shrinkage as a tool to compensate for the shrinkage. The measurements with a coordinate measuring machine and the numerical analysis revealed that the proposed design approach can decrease the dimensional error substantially compared to the conventional 3D printed parts.
Journal Selected Ulas Yaman

Shrinkage compensation of holes via shrinkage of interior structure in FDM process

Ulas Yaman
Journal Selected
03 Sep 2008

GRADUATE STUDENT EDUCATION IN DISCRETE-TIME CONTROL

Istanbul - Turkey

This paper presents an embedded control system course for graduate-student education / research. This course, which is to provide hands-on-experience, employs “lab-at-home” approach where the students are expected to design and implement various embedded control systems at home rather than a formal lab environment.
Ulas Yaman, Serdar Usenmez, Baris R. Mutlu, Melik Dolen, and A. Buğra Koku

GRADUATE STUDENT EDUCATION IN DISCRETE-TIME CONTROL

Ulas Yaman, Serdar Usenmez, Baris R. Mutlu, Melik Dolen, and A. Buğra Koku
22 Jun 2010

Design of advanced motion command generators utilizing FPGA

Ankara - Turkey

In this study, universal motion command generator systems utilizing a Field Programmable Gate Array (FPGA) and an interface board for Robotics and Computer Numerical Control (CNC) applications have been developed.
Thesis Ulas Yaman, Baris R. Mutlu, Melik Dolen, and A. Bugra Koku

Design of advanced motion command generators utilizing FPGA

Ulas Yaman, Baris R. Mutlu, Melik Dolen, and A. Bugra Koku
Thesis
15 Nov 2009

Performance evaluation of different real-time motion controller topologies implemented on a FPGA

Tokyo - Japan

This paper presents a comprehensive comparison of several real-time motion controller topologies implemented on a field programmable gate array (FPGA).
Conference Mutlu, Baris R., Ulas Yaman, Melik Dolen, and A. Bugra Koku

Performance evaluation of different real-time motion controller topologies implemented on a FPGA

Mutlu, Baris R., Ulas Yaman, Melik Dolen, and A. Bugra Koku
Conference
15 Nov 2009

Direct command generation methods for servo-motor drives

Tokyo - Japan

This study focuses on advanced direct command generation paradigms that can be easily incorporated to modern servo-motor drive systems. As an alternative to conventional methods, two new command generation techniques are proposed in this paper.
Conference Ulas Yaman, Baris R. Mutlu, Melik Dolen, and A. Bugra Koku

Direct command generation methods for servo-motor drives

Ulas Yaman, Baris R. Mutlu, Melik Dolen, and A. Bugra Koku
Conference
26 Feb 2010

Polymorphic robotic system controlled by an observing camera

Singapore

Polymorphic robotic systems, which are composed of many modular robots that act in coordination to achieve a goal defined on the system level, have been drawing attention of industrial and research communities since they bring additional flexibility in many applications. This paper introduces a new polymorphic robotic system, in which the detection and control of the modules are attained by a stationary observing camera.
Conference Bilge Koçer, Tugçe Yüksel, Mehmet Ersin Yümer, C. Alper Özen, and Ulas Yaman

Polymorphic robotic system controlled by an observing camera

Bilge Koçer, Tugçe Yüksel, Mehmet Ersin Yümer, C. Alper Özen, and Ulas Yaman
Conference
08 Jul 2010

A novel command generation method with variable feedrate utilizing FGPA for motor drives

HERAKLION - CRETE - GREECE

This paper focuses on a novel command generator for servo-motor drives to be used as an integral part of their motion controllers. The paper was selected as the best paper in the workshop.
Conference Selected Ulas Yaman, Melik Dolen, and A. Bugra Koku.

A novel command generation method with variable feedrate utilizing FGPA for motor drives

Ulas Yaman, Melik Dolen, and A. Bugra Koku.
Conference Selected
13 Apr 2011

Evaluation of compression algorithms for motion command generation

Istanbul - Turkey

This paper focuses on a direct command generation technique for Computer Numerical Control (CNC) machine systems. In this paradigm, higher-order differences of a given trajectory (i.e, position) are computed and the resulting data are compacted via data compression techniques.
Conference Ulas Yaman and Melik Dolen

Evaluation of compression algorithms for motion command generation

Ulas Yaman and Melik Dolen
Conference
27 Feb 2013

A new hardware-in-the-loop simulator for CNC machine applications

Vicenza - Italy

This study focuses on an integrated software and hardware platform that is capable of performing (real-time/non-real-time) hardware-in-the-loop simulation of dynamic systems, including electrical machinery, CNC machine tools.
Conference Serdar Usenmez, Baris R. Mutlu, Ulas Yaman, Ergin Kilic, Melik Dolen, and A. Bugra Koku.

A new hardware-in-the-loop simulator for CNC machine applications

Serdar Usenmez, Baris R. Mutlu, Ulas Yaman, Ergin Kilic, Melik Dolen, and A. Bugra Koku.
Conference
01 Apr 2013

Direct command generation for CNC machinery based on data compression techniques

Ankara - Turkey

This paper presents a direct command generation technique for digital motion control systems. The paper illustrates that the ΔY10 technique, which is suitable for real-time hardware implementation, exhibits satisfactory performance in terms of data compaction achieved in the test cases considered.
Journal Selected Ulas Yaman and Melik Dolen

Direct command generation for CNC machinery based on data compression techniques

Ulas Yaman and Melik Dolen
Journal Selected
21 Jan 2014

New morphological methods to generate two-dimensional curve offsets

Ankara - Turkey

For the purpose of generating 2D curve offsets used in 2.5D machining, four new methods based on morphological operations on different mathematical entities are presented in this paper.
Journal Selected Melik Dolen and Ulas Yaman

New morphological methods to generate two-dimensional curve offsets

Melik Dolen and Ulas Yaman
Journal Selected
03 Apr 2014

A new hardware-in-the-loop simulator for control engineering education

Istanbul - Turkey

As a part of a “lab-at-home” education paradigm for control engineering courses, this paper proposes (and elaborates) a novel hardware-in-the-loop simulator with 3D animation capabilities. The developed software, which can be tailored to simulate any dynamic systems in non-real-time, is designed to work in conjunction with a control hardware. In the paper, the specific application of the software to a graduate-level course is presented within the framework of a final term project involving the control of a satellite tracking antenna.
Conference Serdar Usenmez, Ulas Yaman, Melik Dolen, and A. Bugra Koku

A new hardware-in-the-loop simulator for control engineering education

Serdar Usenmez, Ulas Yaman, Melik Dolen, and A. Bugra Koku
Conference
09 Jun 2014

Advanced motion command generation paradigms for CNC systems

Ankara - Turkey

A novel motion command generation paradigm for digital motion control systems is developed with in the scope of this dissertation. In the paradigm, the tool trajectory is firstly defined with the developed programming language on a host computer and then transferred to the machine with different communication protocols. The language proposed is capable of decompressing the previously compressed motion data via ΔY10 decompression algorithm and generating curve offsets of the base curve in inner and outer directions. With these abilities of the programming language and its hardware processor (VEPRO), the tool trajectory of a machining case can be presented with a few lines of commands. The hardware complexity of the VEPRO is low compared to the ones currently used in computer numerical systems such as Siemens Sinumerik and Fanuc 0i.
Thesis Ulas Yaman

Advanced motion command generation paradigms for CNC systems

Ulas Yaman
Thesis
22 Mar 2015

A gradient-based morphological method to produce planar curve offsets

Ankara - Turkey

Two-dimensional curve offsets have a wide application area ranging from manufacturing to medical imaging. To that end, this paper concentrates on two novel techniques to produce planar curve offsets. Both methods, which are based on mathematical morphology, employ the concept that the boundaries formed by a circular structuring element whose center moves across the points on a base curve comprise the entire offsets of the progenitor.
Journal Selected Ulas Yaman and Melik Dolen

A gradient-based morphological method to produce planar curve offsets

Ulas Yaman and Melik Dolen
Journal Selected
23 Oct 2016

A command generation approach for desktop fused filament fabrication 3D printers

Florence - Italy

This study develops a novel command generation paradigm for desktop fused filament fabrication 3D printers. The proposed command generation paradigm overcomes most of the drawbacks of the conventional design and fabrication pipeline by taking advantage of the high redundancy of the motion trajectories of the printer heads.
Conference Selected Ulas Yaman and Melik Dolen

A command generation approach for desktop fused filament fabrication 3D printers

Ulas Yaman and Melik Dolen
Conference Selected
13 Nov 2016

Dimensional accuracy improvement of fused filament fabrication holes utilizing modified interior

Chiba - Japan

This paper proposes an alternative approach to improve the dimensional accuracy of the holes manufactured with Fused Filament Fabrication desktop 3D printers.
Conference Seyda Simsek and Ulas Yaman

Dimensional accuracy improvement of fused filament fabrication holes utilizing modified interior

Seyda Simsek and Ulas Yaman
Conference
01 Jun 2016

Slice coherence in a query-based architecture for 3D heterogeneous printing

Indiana - USA

We report on 3D printing of artifacts with a structured, inhomogeneous interior. The interior is decomposed into cells defined by a 3D Voronoi diagram and their sites. When printing such objects, most slices the printer deposits are topologically the same and change only locally in the interior. The slicing algorithm capitalizes on this coherence and minimizes print head moves that do not deposit material. This approach has been implemented on a client/server architecture that computes the slices on the geometry side. The slices are printed by fused deposition, and are communicated upon demand.
Journal Selected Ulas Yaman, Nabeel Butt, Elisha Sacks, and Christoph Hoffmann

Slice coherence in a query-based architecture for 3D heterogeneous printing

Ulas Yaman, Nabeel Butt, Elisha Sacks, and Christoph Hoffmann
Journal Selected
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RESEARCH

LABORATORY TEAM
FACULTY

MELİK DÖLEN

Associate Professor

Ulas Yaman

Assistant Professor

STUDENTS

Vahid Haseltalab

RESEARCH ASSISTANT

Mert Keleş

RESEARCH ASSISTANT

Bahar Garehpapagh

RESEARCH ASSISTANT

Uğur Dilberoğlu

RESEARCH ASSISTANT

Matin Ghaziani

RESEARCH ASSISTANT

Yunus Emre Yılmaz

RESEARCH ASSISTANT

RESEARCH PROJECTS

TÜBİTAK - 1001

A Smart- and Hybrid Manufacturing System Utilizing Additive Manufacturing Methods and Machining

The main purpose of the project is to develop a 5-axis hybrid manufacturing system that takes the advantages of traditional machining process and additive manufacturing techniques. The hybrid system, which will be developed for use on desktops, can be easily adapted to different dimensions, thanks to its modular structure and it will provide a suitable environment for testing advanced methods of manufacturing with its open architecture.

TÜBİTAK - 3001

A Novel Design and Fabrication Pipeline for 3D Printers: LIPRO

The main aim of the project is to overcome the disadvantages of the current design and fabrication pipeline of 3D printer systems with a short pipeline and a compact command generation paradigm based on List Processors. This novel pipeline scheme will benefit from the high redundancy of the motion trajectory data of additive manufacturing applications and the query-based CAD/CAM architecture. High redundancy results from the following properties of the motion trajectories: i) the tool trajectory is mostly symmetrical due to the symmetry associated with the artifacts; ii) the simple offsets (biases) among the successive tool paths frequently appear in additive manufacturing over the shells or the interior; iii) there is high coherency between the consecutive slices. Consequently, the size of raw motion data (G-code files in the conventional pipeline) could be reduced and modified easily by making use of these attributes of the motion trajectories in additive manufacturing.

ODTÜ - BAP

Improving the Dimensional Accuracy of 3D Printed Artifacts

An interior design methodology to compensate for the shrinkage in the holes of artifacts fabricated with desktop 3D printers employing Fused Deposition Mod- eling process is presented in this study. In the conventional way of compen- sating, the initial geometry is scaled according to the predictive and statistical models so that the critical dimensions will be more accurate when the part is cooled down. The proposed method employs a completely different paradigm. It constructs various interior structures to compensate for the shrinkage in the holes according to the geometric attributes of the artifacts. In other words, the method utilizes shrinkage as a tool to compensate for the shrinkage. Printed interior line segments, which are directly connected to the perimeter of the hole, simply pull the hole towards the inside of the artifact. In result, the dimensional accuracy of the hole is improved considerably. The measurements with a Coordi- nate Measuring Machine and the numerical analysis revealed that the proposed design approach can decrease the dimensional error substantially compared to the conventional 3D printed parts.

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LIPRO

3B Yazıcılar İçin Yeni Bir Tasarım ve Üretim Akışı: LIPRO

TÜBİTAK 3001 – Başlangıç Ar-Ge Projeleri Destekleme Programı kapsamında desteklenen bu çalışmada 3B yazıcılar için LIPRO başlıklı yeni bir tasarım ve üretim akışı sunulmaktadır. Bu yöntemde, karmaşık iş parçası geometrilerinin parametrik bir biçimde tanımlanması için takım yörüngesi hareketleri yüksek seviyeli bir programlama dili ile üretilmiştir. Yorumlanan program kodları daha sonra bir dizi kinematik kısıtlamaya tabi tutularak takım yörüngesini hesaplamak için gerekli enterpolasyon verilerini oluşturmakta kullanılır. Her hareket kontrolcüsü tarafından ihtiyaç duyulan pozisyon komutlarının senkronize bir şekilde sağlanması için gerçek zamanlı bir enterpolatör kullanılır. Bu kavramı kanıtlamak için, önerilen yöntem Python kodlama dili kullanılarak bir bilgisayara uyarlanmıştır. Yaklaşımın performansı, farklı üretim tekniklerini içeren iki test vakası (örn. Cep frezeleme ve 3B baskı) ile titizlikle değerlendirilmiştir. Bu çalışma, deneysel sonuçlar ile gerçek zamanlı donanım uygulamalarında kendini ispatlamış ve tüm yoğun çalışmalarda tatmin edici bir performans sergileyip yöntemin geniş bir üretim yelpazesi için teknik olarak uygulanabilir olduğunu göstermiştir. Destek ve yardımlardan dolayı TÜBİTAK’a teşekkür ederiz.

Geliştirilen komut üretim yaklaşımı kullanılarak 3B yazıcılar özelinde yeni bir tasarım ve üretim akışı oluşturulmuştur. Python programlama dili ile gerçekleştirilen bu yaklaşımda List veri yapısı sıklıkla kullanıldığı için akışa LIPRO (List Processor) adı verilmiştir. Geleneksel tasarım ve üretim akışından farklı olarak nesneler Python dili ile geometrik olarak tanımlanmaktadırlar. Tanımlanan geometride ufak değişiklikler yaparak aynı kod parçasıyla farklı nesneler üretilebilmektedir. Dolayısıyla nesneler doğrudan modelleme yerine dolaylı modelleme yardımıyla tanımlanmaktadırlar. Dolaylı modelleme yaklaşımının kullanılamadığı durumlarda (örneğin karışık geometriye sahip parçalar) nesnelerin dilimleri bir veri yapısı içerisinde LIPRO’ya beslenir. Böylelikle LIPRO’nun diğer avantajlarından faydalanılmaya devam edilir. İki farklı eklemeli üretim teknolojisi (FDM ve DLP) üzerinde gerçekleştirilen LIPRO’nun uygulama detayları takip eden alt bölümlerde anlatılmıştır.

 

1. FDM Uygulaması

LIPRO’nun FDM üzerindeki uygulaması için Ultimaker 2 Go isimli masaüstü FDM yazıcısı kullanılmıştır. Bu yazıcı sadece PLA malzemesini kullanabildiği için çalışma sırasında da sadece PLA malzemesi kullanılmıştır. Geleneksel yaklaşımda üretilen G komutları SD kart aracılığıyla yazıcıya aktarılmaktadır. Sonrasında yazıcının genel denetimini sağlayan Arduino Mega mikrokontrolcüsü G komutlarını işleyerek üretimi gerçekleştirmektedir ve üretim sırasında herhangi bir değişiklik yapmak mümkün değildir. LIPRO’nun Tip 2 uygulamasını (mikrokontrolcünün aradan çıkarılması) bu yazıcı üzerinde yapmak uzun zaman gerektireceği için Tip 1 (sadece LIPRO koşan bir tek kartlı bilgisayar kullanılması) ve Tip 2 (üretimin tamamı için gereken G komutlarının LIPRO ile üretilip SD kart ile aktarılması) arasında kalan bir uygulama gerçekleştirilmiştir. Bu ara uygulamada Arduino Mega’ya USB üzerinden bağlanan Raspberry Pi 3 bilgisayarı kullanılmıştır. Raspberry Pi 3 üzerinde koşan LIPRO her katman için üretmiş olduğu G komutlarını Arduino Mega’ya beslemektedir. Dolayısıyla katman sayısı kadar mikrokontrolcü ve tek kartlı bilgisayar arasında transfer gerçekleşmektedir. Komutlar gönderildikten sonra Arduino Mega bunları işleyerek geleneksel akışta olduğu gibi üretimi gerçekleştirmektedir. Bu uygulamada LIPRO’nun sunmuş olduğu avantajlardan yararlanmak mümkündür.

LIPRO’nun başarımını göstermek amacıyla Şekil 1’de gösterilen parça geleneksel ve LIPRO yaklaşımlarıyla üretilmiştir. LIPRO ile üretim sırasında Rasberry Pi 3 üzerinde koşturulan Python dosyasının ana hatları Şekil 2’de sunulmuştur. Parça ile ilgili geometrik bilgiler ve baskı değişkenleri girildikten sonra Arduino Mega ile iletişim kurulmakta ve üretim başlatılmaktadır. PLA malzemesi ekstrüde edilmeden önce başlangıç için gerekli ayarlar yapılmaktadır. Üretim için gerekli komutlar katmanlar halinde yazıcının mikrokontrolcüsüne gönderilmektedir. Üretim bittiğinde gerekli komutlar çalıştırılarak yazıcı bir sonraki üretime hazır hale getirilir.

Şekil 1. LIPRO ile üretilecek örnek parça

Şekil 2. LIPRO’nun FDM uygulamasının ana dosyası

Şekil 1’de sunulan parçanın üretimi için yazılan LIPRO üretim kodunun ana hatları Şekil 3’te sunulmuştur. Polygon fonksiyonu kare oluşturmak için kullanılmakta olup Offset fonsiyonu yardımıyla katmanların kabukları oluşturulmaktadır. Böylelikle istenilen kalınlık elde edilir. Üretilen kafa yörüngeleri Gcode fonksiyonu yardımıyla G komutlarına dönüştürülür ve SendGcodes ile 3B yazıcıya gönderilir. Bu işlemler katman sayısı kadar tekrarlanır. Parça özelinde çalıştırılan homojen dönüşüm komutu ile üçgen yapı her katmanda 0.1 radyan döndürülür ve Şekil 1’de sunulan parça elde edilir. Geleneksel ve LIPRO yaklaşımları ile üretilen parçalar Şekil 4’te sunulmuştur. Parçalar arasında herhangi bir fark bulunmamaktadır. İki yaklaşımda kullanılan dosyaların boyutları (kB) Tablo 1’de verilmiştir. LIPRO’un bu konudaki üstünlüğü açıkça görülmektedir.

Şekil 3. LIPRO’nun FDM uygulamasının üretim fonksiyonu

Şekil 4. Geleneksel yaklaşım (Sol) ve LIPRO yaklaşımı (Sağ) ile üretilen parçalar

Tablo 1. Geleneksel ve LIPRO yaklaşımlarında kullanılan dosyaların boyutu (kB)

  Geleneksel Yaklaşım LIPRO Yaklaşımı
CAD Dosyası 244 –
STL Dosyası 378 –
Üretim Dosyası 3079 (G komut dosyası) 8 (Python dosyaları)

LIPRO’nun diğer büyük avantajı olan esnekliği göstermek amacıyla Şekil 3’te sunulan dosya üzerinde ufak değişiklikler (kenar sayısı, dönme açısı, vb.) yaparak Şekil 5’te gösterilen farklı parçalar üretilmiştir.

Şekil 5. Aynı LIPRO dosyasıyla üretilen parçalar

 

Örnek bir FDM uygulaması aşağıdaki videoda sunulmuştur.

LIPRO – FDM Uygulaması

 

 

2. DLP Uygulaması

LIPRO’nun DLP üzerindeki uygulaması için B9Creator v1.2 isimli masaüstü DLP yazıcısı kullanılmıştır. Geleneksel DLP tasarım ve üretim yaklaşımında üretilecek olan parçanın STL dosyası elde edildikten sonra, yazıcının kendi yazılımı aracılığıyla, parçanın tabla üzerindeki yerleşimi yapılır. Yazılımın ilk modülünde yapılan bu dizim sonrasında ikinci modül kullanılarak istenen kalınlıkta dilimleme yapılır ve parçanın katmanlarının görüntüleri oluşturulur (1920:1080). Siyah ve beyaz olan bu görüntülerin boyutları (6 MB) fazla olduğu için katmanların tamamı (500 katmanlı bir üretimin toplamı yaklaşık 3 GB tutmaktadır.) özel bir sıkıştırma yöntemi kullanılarak sıkıştırılır ve kabul edilebilir boyutlara (2-3 MB) getirilebilir. Sıkıştırma yöntemleriyle ilgili ayrıntılı çalışmalar uluslararası konferans bildirisinde tartışılmıştır (Yaman vd., 2017). Yazılımın üçüncü modülü ile üretim başlatılır ve katmanlar sırasıyla projektöre yansıtılır. Görüntünün beyaz olan kısımlarına denk gelen fotopolimerler kürlenerek katılaştırılır. Katman sayısı kadar tekrarlanan bu işlem neticesinde nesne üretilir. FDM yaklaşımında olduğu için üretim başlatıldıktan sonra herhangi bir tasarım ya da parametre değişikliği yapmak mümkün değildir.

Şekil 6’da kullanılan B9Creator v1.2 DLP yazıcısının ana parçaları gösterilmiştir: projektör (1), Arduino Uno ve motor sürücüleri kartı (2), z ekseni adım motoru (3), x ekseni DC motoru (4), vidalı mil (5) ve eksen sonu anahtarları (6).

 

 

 

Şekil 6. DLPyazıcısının alttan ve önden görünümü

FDM yazıcılarına göre elektro-mekanik mimarisi daha basit olan bu DLP yazıcısı üzerinde LIPRO’nun Tip 2 uygulaması gerçekleştirilmiştir. Oluşturulan yeni mimari Şekil 7’de sunulmuştur. Raspberry Pi 3 ile motorları sürebilmek için üzerine bir motor sürücü kartı takılmıştır. Adım motoru ve DC motoru sürebilmek için gerekli bağlantılar yapılmıştır. Eksenlerin sıfır konumlarını okuyabilmek için kullanılan anahtarlar sayısal girdiler olarak Raspberry Pi 3’e beslenmiştir. Projektör de HDMI çıkışı ile tek kartlı bilgisayara bağlanmıştır.

Şekil 7. LIPRO’nun DLP uygulamasının elektro-mekanik bağlantıları

DLP uygulaması için Rasberry Pi 3 üzerinde koşturulan Python kodunun ana hatları Şekil 8’de verilmiştir. FDM uygulamasında olduğu gibi üretimi başlatmak ve sonlandırmak için birçok ayarın gerçekleştirilmesi gerekmektedir. Üretim fonksiyonunun ayrıntıları ise Şekil 9’da sunulmuştur. Katman sayısı kadar tekrarlanan kürleme işlemleri sonrasında parça kullanıma hazır olmaktadır.

Şekil 8. LIPRO’nun DLP uygulamasının ana dosyası

Şekil 9. LIPRO’nun DLP uygulamasının üretim fonksiyonu

Geleneksel ve LIPRO yaklaşımları ile üretilen parçalar Şekil 10’da sunulmuştur. Parçalar arasında herhangi bir fark bulunmamaktadır. İki yaklaşımda kullanılan dosyaların boyutları (kB) Tablo 2’de verilmiştir. LIPRO’un bu konudaki üstünlüğü açıkça görülmektedir.

Şekil 10. Geleneksel yaklaşım (Sol) ve LIPRO yaklaşımı (Sağ) ile üretilen parçalar

Tablo 2. Geleneksel ve LIPRO yaklaşımlarında kullanılan dosyaların boyutu (kB)

  Geleneksel Yaklaşım LIPRO Yaklaşımı
CAD Dosyası 162 –
STL Dosyası 223 –
B9 Tabla Dosyası 1 –
Üretim Dosyası 246 (B9 dosyası) 19 (Python dosyaları)

 

FDM uygulamasında olduğu gibi aynı Python kodunda ufak değişiklikler yapılarak farklı parçalar DLP yazıcısı ile de üretilebilmektedir. Örnek parçalar Şekil 11’de sunulmuştur. En sağdaki parçanın üretimi sırasında fotopolimer şişesi çalkalanmadığı için şeffar bir parça elde edilmiştir. Ayrıca bu parçanın üretimi sırasında katmanlar belirli bir yükseklikten sonra döndürülmüştür.

Şekil 11. Aynı LIPRO dosyasıyla üretilen parçalar

Örnek bir DLP uygulaması aşağıdaki videoda sunulmuştur.

LIPRO – DLP Uygulaması

.06

TEACHING

CURRENT
  • Fall
    2019

    ASSISTANT PROFESSOR

    ODTÜ

    I will be teaching ME 533 - Computer-Aided Design and ME 414 - System Dynamics in the upcoming Fall semester.
TEACHING HISTORY
  • 2015
    2019

    ASSISTANT PROFESSOR

    ODTÜ

    I taught the following courses:

    - ME 202, Fall 2015

    - ME 202, Spring 2016

    - ME 407, Spring 2016

    - ME 202, Fall 2016

    - ME 495, Fall 2016

    - ME 202, Spring 2017

    - ME 533, Spring 2017

    - ME 303, Fall 2017

    - ME 495, Fall 2017

    - ME 202, Spring 2018

    - ME 533, Fall 2018

    - ME 495, Fall 2018

    - ME 202, Spring 2019

    - ME 533, Fall 2019

    - ME 414, Fall 2019
  • Summer
    2015

    VISITING ASSISTANT PROFESSOR

    Purdue University

    I taught CS 250 - Computer Architecture in the Department of Computer Science.
  • 2007
    2014

    TEACHING ASSISTANT

    ODTÜ

    I assisted the following courses at least for one semester: ME 200, ME 205, ME 206, ME 210, ME 212, ME 303, ME 304, ME 307, ME 308, ME 407, ME 410, ME 414, ME 440, ME 445, ME 448, and ME 534.
.07

ABOUT

PERSONAL DETAILS
ODTÜ, Department of Mechanical Engineering, A-205, 06800, Çankaya, Ankara, Turkey
mapiconimg
uyaman@metu.edu.tr
+90 312 210 5289
I am an Assistant Professor in the Department of Mechanical Engineering at ODTÜ.

BIO

ABOUT ME

I am an Assistant Professor of Mechanical Engineering at ODTÜ since October 2015. I received my PhD (2014), MSc (2010), BSc (2007) in Mechanical Engineering, and Minor in Mechatronics (2007) degrees from the same university. I was a Visiting Assistant Professor of Computer Science at the Purdue University from July 2014 to October 2015. My research interests include 3D printing and additive manufacturing, CAD/CAM architectures, command generation, FPGA-based embedded systems and computational geometry for design and manufacturing.

HOBBIES

Bağlama - Cycling - Novels - Stamps - Drawing - Beşiktaş