Ulas Yaman

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

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. Display Omitted We explore 3D Voronoi-based heterogeneous printing.We utilize Euler loops to minimize non-extruding fast travels.The motion paths of consecutive slices are almost the same.The motion paths are not generated from scratch at every slice.Only 3 local cases can arise when updating the motion paths.

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

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. The success of the software (along with the methodology) is rigorously evaluated through the information collected in three academic semesters including the course instructors feedback and the questionnaires filled out by the students.

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

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.

Direct command generation methods for servo-motor drives

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. In the first method, higher-order differences of a given trajectory (i.e. position) are computed and the resulting data are compressed via lossless data compression techniques. Besides conventional approaches, a novel compression algorithm is also introduced in the paper. With respect to the second method, the command trajectory is first divided into segments according to the inflection points. The segments are then approximated using various polynomial techniques. The sequence originating from modeling error is included to the generated series. These two command generation techniques are then implemented using Field Programmable Gate Arrays (FPGAs) and their performances are evaluated according to the resources used in FPGAs and the speed of computation.

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

This paper presents a comprehensive comparison of several real-time motion controller topologies implemented on a field programmable gate array (FPGA). Controller topologies are selected as proportional-integral-derivative controller with command feedforward, sliding mode controller, fuzzy controller, and a hysteresis controller. Controllers and other necessary modules are developed using Verilog HDL and they are implemented on a ML505 development board with a Xilinx Virtex-5 FPGA chip. In order to take full advantage of FPGA and to provide a more accurate comparison, an (soft-core) embedded processor is not employed in the design. The developed modules, which include PWM generator, quadrature encoder decoder, velocity estimator, reference profile generator etc, are fully tailored for the application. To perform the necessary calculations for certain controller topologies, an open-core floating point unit (FPU) is also adopted to the design. The performances of the aforementioned controllers are rigorously evaluated via a hardware-in-the-loop simulation of a field-oriented induction motor system.

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

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. In this approach, once the dynamics of the plant to be controlled is defined via C++ language, the resulting code is cross-compiled automatically on a PC. Executable files along with the necessary drivers are downloaded onto the composite hardware platform that consists of a Field Programmable Gate Array (FPGA) along with a powerful DSP board. The paper elaborates the overall performance of this novel hybrid HILS platform on a CNC machine tool application.

Evaluation of compression algorithms for motion command generation

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. As a part of the command generation scheme, the paper also introduces a new data compression technique titled ΔY10. Apart from this new method, the performances of the proposed generator employing different compression algorithms (such as Huffman Coding, Arithmetic Coding, LZW, and ΔY10) are also assessed through a test case. The paper shows that the ΔY10 technique, which is suitable for real-time hardware implementation, exhibits much better performance than its counterparts in terms of data compaction achieved.

Generation of patterned indentations for additive manufacturing technologies

Abstract This article proposes a novel approach to generate patterned indentations for different additive manufacturing methodologies. Surface textures have many practical applications in various fields, but require special manufacturing considerations. In addition to conventional manufacturing processes, additive processes have also been utilized in the last decade to obtain textured surfaces. The current design and fabrication pipeline of additive manufacturing operations have many disadvantages in that respect. For instance, the size of the design (CAD) files grows considerably when there are detailed indentations on the surfaces of the artifacts. The presented method, which employs morphological operations on a sequence of binary images representing the cross-sections of the printed artefact, overcomes such problems while fabricating the textured objects. Furthermore, the presented technique could be conveniently implemented using the existing hardware resources of almost any three-dimensional printer.

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

This study develops a novel command generation paradigm for desktop fused filament fabrication 3D printers. In the conventional approach, designed artifact in CAD software is saved as an STL file, which is still a de-facto file standard in the field, and then imported into the CAM software of the corresponding 3D printer. After adjusting the printing parameters (feed rate, layer thickness, infill percentage, etc.), the G-code file is generated within the CAM software and it is transferred to the printer for the fabrication. There are various problems of this conventional design and manufacturing pipeline of 3D printers. The proposed command generation paradigm overcomes most of these drawbacks of the conventional scheme by taking advantage of the high redundancy of the motion trajectories of the printer heads. These paths are modeled with the available functions of the scheme and processed on the printer side. The main advantage is that the generated command trajectory file can easily be modified as opposed to the G-code files and be used for the fabrication of different artifacts.