Accuracy Of Shapes Research Articles

Software based analysis of angularity error for polygonal micro-cavities produced by die-sinking EDM

This paper aims to present the results of an investigation on the angularity error calculated for micro polygonal cavities i.e. triangular, square, pentagonal and hexagonal cavities. The investigation began by machining of micro polygonal shapes in series of three on steel sample using 400 µm tungsten carbide electrode in die-sinking EDM integrated with e-pulse supply and précised multi-axes electrode movement enabling micro-machining capabilities. After that the machined micro-cavities and their geometry were examined by an Olympus optical microscope and the accuracy of shapes has been evaluated after analyzing angularity error of these geometries by profile projector and olympus analysis five software. It was found that the average angularity error of triangular micro cavities is 4.34° while that for square, pentagonal and hexagonal micro cavities are 1.33°, 7.93° and 8.74° respectively. On the basis of obtained data, it is found that the square cavities have maximum angular accuracy as compared to others. It may be attributed to the fact that there is lesser presence of secondary discharge in case of square cavities and limited tool travel.

Razvoj nove CNC brusilice za 3+2 osno brušenje profilnih koturatih glodala

Due to the great expansion of woodworking, profile tools manufacturing has become current and in demand. In wood industry there are two large groups of tools: rotary and spindle milling cutters that can be profile or flat. The technology of making profile rotary milling cutters requires, apart from cutting, turning, milling, 5-axis grinding operation that is performed on a 5-axis CNC grinding machine with the A'OXYZC configuration.It is a machine of a very complex kinematics and high cost-price. The paper presents a new machine that has been built for 3+2-axis grinding - Profilator 100,used for industrial manufacturing of rotary and spindle profile milling cutters. The accuracy of measures and shapes of the profile cutters built on Profilator 100 is of a high level and in industrial exploitation the difference is not observed between the profile cutters built on 5-axis CNC grinding machines. Regarding technoeconomic cost-effectiveness, production costs of Profilator 100 are lower even by ten times compared to the cost-price of 5-axis CNC grinding machines of renowned world manufacturers such as Schneeberger and Volmer.

Machining Temperature and Accuracy of Magnesium Alloy AZ31 with Deep-Hole Small Drilling

In recent years, magnesium-based materials have become expected to replace conventional engineering plastics as next-generation industrial materials to protect the global environment. However, in the production technology, problems of cracking and unstable accuracy in drilled hole shapes persist in plastic molding and machine tool processing; many studies have been conducted to address these problems. In dry machining ignition can be caused by the material, so wet machining is the prevalent method. However, it is necessary to establish a machining method with improved environmental parameters, considering the impact of oil mist and waste oil treatment on woks. In this study, the relationship between machining temperature and the accuracy of hole shapes in magnesium alloy AZ31 is investigated with four types of drills: high-speed steel, cemented carbide (K-Base), diamond-like carbon (DLC; K-Base), and TiN-coated cemented carbide (K-Base). The drill tip angle is set to 116°, 118°, or 120°. The work material used is the extruded AZ31 magnesium alloy. To evaluate the hole shape accuracy, squares of 80 × 80 mm are used. The cutting temperature is measured over an area of 12 × 30 mm. The work material is drilled using a dry method with a 3-mm-diameter drill having the aspect ratio (L/D) of 10. The tool protrusion length of 50 mm and cutting speed of 20 m/min are fixed, and the tool feed rate and drill step amount are changed. The experiment is repeated 3 times. The burr generated around the loophole on the back surface of the test material after the test is evaluated with a criterion burr height H of 0.02 mm. Furthermore, the average roughness (Ra) of the centerline is measured on the inner surface of the hole with a contact-type roughness meter. The results show that when using the three drill point angles of 116°, 118°, and 120° in the drill step, no burrs form at the exit of the drill hole. Carbide tools form burrs when the feed rate exceeds 30 mm/min and the step amount exceeds 20 mm. TiN tools are highly accurate up to a tip angle of 118°, while DLC tools have lower cutting forces and yield better finished surfaces than the other tools.

Development Of A First-Person View-Based Korean Sign Language Education System Using VIVE Hand Tracking

In this study, using VIVE and Tracking, we developed a ‘first-person view-based Korean sign language education system’ that guides sign language handshapes using a 3D virtual hand from the user's point of view and then evaluates the accuracy of the handshapes that learners perform. The learning effects of a Korean sign language education system that guides sign language handshapes using 3D virtual hands in a virtual space and a system that only learns with a teacher's lecture video in a virtual space were compared and analyzed. The number of times the two groups of participants tried to make the sign language correctly was measured. Then, the measurement results were compared and analyzed and interviews also conducted. As a result of the experiment, the ‘first-person view-based Korean sign language education system’ demonstrated that some sign language handshapes, which are not easy for participants to make, were implemented faster and more accurately than traditional learning methods. Therefore, if this system is used, it is expected that sign language learners will be able to learn more intuitively through the first-person perspective. Furthermore, it is expected that learning effects can be improved through the ability of being able to judge whether users are making the correct shapes with their hands. In addition, since it is possible to evaluate the accuracy of the hand shapes, it is believed that single-person learning, which was not easy in the existing sign language education paradigm, will become possible. However, for the sign language examined in the experiment, some showed significant differences while others were less meaningful. These were analyzed because the difficulty of the learning contents used in the experiment was not high. In future research, in order to more accurately verify the effectiveness of the sign language education system using hand tracking and 3D virtual hand guidance, we intend to conduct an experiment implementing learning content with more complex sentences

Analisis Ornamen Kerawang Gayo Pada Rumah Adat Pitu Ruang Kabupaten Aceh Tengah

Penelitian ini bertujuan untuk mendeskripsikan Ornamen Kerawang Gayo dari indikator bentuk, wrna, mkna dan pnempatan yang dilaksanakan di rumah adat Pitu Ruang. Penelitian ini merupakan penelitian deskriptif kualitatif. Subjek penelitian ini adalah 10 motif Ornamen Kerawang Gayo yaitu motif Emun berangkat (Awan berarak), Puter Tali (Putar Tali), Pucuk Ni Tuis (Pucuk Rebung), Emun Beriring, Tekukur, Bintang Ulen (Bintang dan Bulan), Ulen-Ulen (Bunga Bulan), Bunge Ni Terpuk (Bunga Kuncung), Bunge Kemang (Bunga yang sedang kembang) dan Emun Berkune. Ketepatan bentuk, warna, makna, dan penempatan menjadi objek dalam penelitian ini. Metode pengumpulan data yang digunakan adalah observasi, dokumentasi, dan wawancara. Analisis data yang digunakan yaitu teknik analisis deskriptif kualitatif. Hasil penelitian ini menunjukkan bahwa ketepatan bentuk, warna, makna dan penempatan pada Ornamen Kerawang Gayo di rumah adat Pitu Ruang sudah sesuai dengan bentuk aslinya. Seluruh motif yang terdapat pada rumah adat Pitu Ruang memiliki makna yang berkaitan dengan kehidupan masyarakat Gayo, dan penempatan di rumah adat Pitu Ruang juga sudah tepat penempatannya.

Accurate profile measurement method for industrial stereo-vision systems

PurposeProfile measurement with boundary information plays a vital role in the detection of quality in the assembly of aviation parts. The purpose of this paper is to improve the evaluation accuracy of the aerodynamic shapes of airplanes, the profiles of large-sized parts need to be measured accurately.Design/methodology/approachIn this paper, an accurate profile measurement method based on boundary reference points is proposed for the industrial stereo-vision system. Based on the boundary-reference points, the authors established a priori constraint for extracting the boundary of the measured part. Combining with the image features of background and the measured part, an image-edge compensation model is established to extract the boundary of the measured part. The critical point of a laser stripe on the edge of the measured part is extracted corresponding to the boundary constraint. Finally, as per the principle of binocular vision, the profile of the measured part is reconstructed.FindingLaboratory experiments validate the measurement accuracy of the proposed method which is 0.33 mm. In the analysis of results between the measured data and the theoretical model, the measuring accuracy of the proposed method was found to be significantly higher than that of the other traditional methods.Practical implicationAn aviation part was measured in the part-assembly shop by the proposed method, which verified the feasibility and effectiveness of this method. The research can realize the measurement of smooth surface boundary which can solve existing profile reconstruction problems for aviation parts.Originality/valueAccording to the two-dimensional contour constraint, critical points of the laser strip sequence at the edge of measured part are extracted and the accurate profile reconstruction with the boundary is realized.

Nonlinear dynamics of a Z-shaped structure with validated global analytical mode shapes

The nonlinear partial differential governing equations of the planar motion of a Z-shaped structure are derived using Hamilton's principle. The 1:2 internally resonant global analytical mode shapes are validated by figure contrast and the modal assurance criterion (MAC). The partial differential governing equations are truncated into a two-degree-of-freedom ordinary differential system with the validated resonant global analytical mode shapes, and they are further investigated for internal and simultaneous primary resonances. The steady-state responses are studied, and numerical simulations of the system are performed. Complex nonlinear phenomena in the system, such as jumps, bifurcations, quasiperiodic motion and chaos, are observed under specific parameters. The parametric rule of these phenomena obviously depends on the accuracy of mode shapes. This work proposes a nonlinear analysis based on the quantitative validation of mode shapes, which may provide new insights into the optimal design of the parameters and the precise control of the motions of Z-shaped or other multibeam structures in engineering.

Computer aided tool design for micro-ECM

This paper reports the development of a computer aided system for micro-ECM process to design tools to produce accurate internal features on workpiece. Mathematical model has been developed to compute the inter-electrode gap (IEG) for chosen shape of tool and process conditions. Axi-symmetric tools of different profiles such as cylindrical, conical, hemispherical have been analysed to predict the shapes of work cavities. Model is validated with the reported results and some experiments conducted by us on typical tool shapes. Parametric studies have been carried out to study influence of various process variables on the accuracy of cavity shapes. Based on these studies, guidelines for improving profile accuracy in micro-ECM have been suggested.

Interactive sonification of images in serious games as an education aid for visually impaired children

AbstractThe paper presents an application for interactive sonification of images intended for use on mobile devices in education of blind children at elementary school level. The paper proposes novel sonification algorithms for converting colour and grayscale images into sound. The blind user can interactively explore image content through multi‐touch gestures and select image sub‐regions for sonification with real‐time control of the synthesized sound parameters such as amplitude, frequency and timbre. Additionally, images may contain text fields read by text‐to‐speech synthesizer. The usability of one of the proposed sonification schemes is tested by collecting data on the tracking accuracy and recognition speed of basic shapes, such as lines, curves, as well as figures and simple functions. In order to facilitate the learning process for blind children, a number of games were proposed that use the devised sonification schemes. The first game—“Hear the Invisible”—is intended for two players—one child draws a shape and the task of the other one is to guess the displayed shape by means of the available sonification methods. The second proposed game is “Follow the Rabbit” and is intended for a single player who tracks a colourful “Rabbit” that runs along a path representing a given geometric shape. The obtained results show that the proposed sonification methods allow to reach previously unattainable levels of flexibility in exploration of shapes and colours. The main application of the described interactive tool is to teach geometry and mathematics in schools for blind children. The developed games are meant to enhance the learning process and motivate the children. Practitioner NotesWhat is known about the topic Sonification is a generic term for data‐based non‐speech sound generation. Interactive sonification is a relatively fresh area of study, where the listener heavily influences the process of sound synthesis. Earlier studies on sonification and educational computer games have shown that it is possible to demonstrate shapes such as plots and geometry using only non‐verbal sounds. What the paper adds The paper proposes an interactive sonification algorithm that can be used on greyscale or colour images using additive synthesis and the HSV colour representation. The presented software also allows to record and analyse user interaction with the images, making it a good research tool for current and future sonification algorithms. The paper presents a pilot study with blind children using two games that improve the learning process of the proposed algorithms. Implications for practice and/or policy Once the software is openly released it can be easily installed on any Android OS device to allow blind users to analyse images by touch. The proposed games train the users the basics of the sonification algorithm in a competitive context. The software can be especially useful in education of blind children, eg, in teaching geometry, math and in training visual and spatial imagination.

Quantitative validation of the analytical mode shapes of a beam-like structure with a Z-shaped configuration

Beam-like structures are widely used in engineering. The accuracy of the analytical mode shapes of these structures is important for studying their dynamic characteristics. A method is presented in this study to theoretically obtain and quantitatively validate the analytical mode shapes of a beam-like structure with a Z-shaped configuration. The governing equations and boundary conditions of the structure’s planar motion are derived using Hamilton’s principle. Frequencies and analytical mode shapes of the structure are theoretically obtained and compared with the numerical results from finite element method. The comparison of frequencies and modal assurance criterion is used to quantitatively validate the analytical mode shapes. Examples are presented to show the analytical mode shapes of Z-shaped beams with different fold angles. The proposed method is useful for improving the accuracy of analytical mode shapes’ which is beneficial to the design and control of beam-like structures in engineering fields.

Development of Neo-Ptero Tailless Micro Aircraft

Unmanned air vehicles (UAV) have been used for many years and it mainly focus on military purposes. Numerous UAV development have been popular worldwide because the low in development cost, operating cost and ability to provide accurate surveillance information and it is a better option for performing reconnaissance missions in hostile environment. However, in the past years a new type of UAV has appeared that possessed lighter weight and smaller in size and it is categorized as a micro unmanned air vehicle (μ-UAV). Although the nonautonomous ready-to-fly tailless μ-UAV exists among local universities, the development of non-autonomous ready-to-fly tailless μ-UAV is still open to be explored. Thus, this project demonstrates the development of the non-autonomous ready-to-fly tailless μ-UAV named as Neo-Ptero. A special CNC hot wire cutter machine was used in the Neo-Ptero fuselage and wing development in which has evidently produced high accuracy of shapes and geometry based on the CAD design. A 3D printing process was used to produce few parts in the Neo-Ptero μUAV model. The model was equipped with on shelves RC components for future flight testing purpose. The actual Neo-Ptero weigh around 1.3kg and has a wingspan of 120.6cm.

The Study of Soundproofing Properties of Wood Polymer-Sand Composite

The development of woodworking and furniture industry in the past twentieth century was largely due to the launch of the production of a large group of artificial materials, now classified as wood-polymer composites. Diversity and renewability of the resource base, convenience and cost-effectiveness of wood-polymer composites (WPC) are the main prerequisites for the development of this group of materials. Fillers in thermoplastic wood-polymer composites may be present in a variety of forms. At this stage industrial WPCs are manufactured mainly from small fractions - wood flour and sawdust. This provides a high technological plasticity of production, namely - the possibility of manufacturing products by extrusion and casting methods, a variety of geometric shapes and even with a small thickness of the walls of the structures. However, this is true if we focus on the maximum possible mechanical properties and accuracy of geometric shapes of finished products. If we focus production on the manufacture of sound-proofing WPC, then almost any wood waste can be used for the filling of such composites. To study and predict sound-proofing properties of wood polymer-sand composite (WPSC), a corresponding mathematical model was developed. It is found that with an increase in the thickness of the polymer-sand coating, the coefficient of sound proof significantly increases. For example, a coating thickness of only 4 mm, increases the sound-proofing properties of a wood sample from 16 to 35 dB, thus the sound-proofing properties of the WPSC are improved by half compared to pure wood.

Researches on Temperature Control Strategy of SMHS-Type 3D Printing Based on Variable Universe Fuzzy Control

Selective micro heat sintering (SMHS)-type 3D printing technology is a widely applied method in rapid prototyping, which uses an electric heating component to sinter non-metallic powder. It requires precise control of the heating component’s energy and its sintering time. Temperature is one of the key factors that affect the forming quality of fused-type 3D printing technology. Aiming at the nonlinear and time-delay characteristics of temperature control in fused-type 3D printing, a fuzzy control method based on variable universe fuzzy control was studied. This fuzzy control method adopts a set of nonlinear expansion-contraction factors to make the variable universes change with the adaptive error, which can help acquire adaptive temperature adjustment in the rapid prototyping process control. The results of the simulation and experiment showed that the controlled temperature response was faster, the overshoot was smaller, and the stability was better compared to the conventional fuzzy proportion integration differentiation (PID) algorithm after the temperature reached the target temperature. The printed results indicated that the universe fuzzy PID control can effectively improve the accuracy of the workpiece shapes and that the density distribution of the workpiece is increased, which can help improve the forming quality.

Improved curvature-based registration methods for high-precision dimensional metrology

Multiple measurements using various data acquisition systems are generally required to substancially enhance measurement accuracy, reliability and holisticity of freeform shapes. The obtained multiple measurement data of the shape are transformed and fused into a common coordinate system within a registration technique involving coarse and fine alignments. Standardized methods have been established for fine registration such as Iterative Closest Points (ICP) and its variants. For coarse registration, no conventional method has been adopted yet despite a significant number of techniques which have been developed in the literature to supply an automatic rough matching between data sets.The work presented in this paper proposes an improvement of registration techniques by the consideration of new discrete curvature parameters. Two main issues are addressed in this paper: the coarse registration and the fine registration. For coarse registration, two novel automated methods based on the exploitation of discrete curvatures are presented: an enhanced Hough Transformation (HT) and an improved Ransac Transformation. The use of curvature features in both methods aims to reduce computational cost. For fine registration, a new variant of ICP method is proposed in order to reduce registration error using curvature parameters. A specific distance considering the curvature similarity is combined with Euclidean distance to define the distance criterion used for correspondences searching. Additionally, the objective function is improved by combining the point-to-point (P-P) minimization and the point-to-plane (P-Pl) minimization with automatic weights. The algorithms are applied on simulated and real data performed by a computed tomography (CT) system. The obtained results reveal the benefit of the proposed improved curvature-based registration methods.

Research of Methods of Accuracy Increase of Building Weld-Fabricated Constructions

Investigation of methods of quality improvement of weld-fabricated building constructions. It is emphasized, this issue is subject to economical, social-psychological and technical factors. To the maximum extent, quality of weld-fabricated building constructions is affected by observance of requirements for accuracy of size and shapes. Accuracy of size and shapes is subject to the values of welding deformation resulting from nonuniform heating of work-pieces in the welding process and of welding heat input. The maximum heat input is observed in the process of manual (MMA) welding, the minimum heat input is a feature of mechanized (Mig/Mag) welding). Use of mechanized methods of welding will reduce welding deformation level and improve accuracy to size of construction.Experimental investigations of butt and fillet shapes have verified the conclusion.

Comparative Analysis of Electroencephalogram-Based Classification of User Responses to Statically vs. Dynamically Presented Visual Stimuli

Emotion is an important part of human and it plays important role in human communication. Nowadays, as the use of machine getting more common, the human computer interaction (HCI) has become important. The understanding of user could bring across a better aiding machine. The exploration of using EEG in understanding human is widely studied for benefit in several fields such as neuromarketing and HCI. In this study, we compare the use of 2 different stimuli (3D shapes with motion vs. 2D emotional images that are static) in attempting to classify positive versus negative feelings. A medical-grade 9-electrode Advance Brain Monitoring (ABM) B-alert X10 is used as the brain-computer interface (BCI) acquisition device to obtain the EEG signals. 4 subjects are involved in recording brain signals during viewing 2 types of stimuli. Feature extraction is then applied to the acquired EEG signals to obtain the alpha, beta, gamma, theta and delta rhythms as features using time frequency analysis. Support vector machine (SVM) and K-nearest neighbors (KNN) classifiers are used to train and classify positive and negative feelings for both stimuli using different channels and rhythms. The average accuracy of 3D motion shapes are better than the average accuracy of the 2D static emotional images for both SVM and KNN with 69.88% and 56.35% using SVM for 3D motion shapes and emotional images respectively, and also 65.31% and 55.45% using KNN for 3D motion shapes and emotional images respectively. This study shows that the parietal lobe are more informative in the classification of 3D motion shapes while the Fz channel of the frontal lobe is more informative in classification of 2D static emotional images.

Probing-error compensation using 5 degree of freedom force/moment sensor for coordinate measuring machine

A new probing and compensation method is proposed to improve the three-dimensional (3D) measuring accuracy of 3D shapes, including irregular surfaces. A new tactile coordinate measuring machine (CMM) probe with a five-degree of freedom (5-DOF) force/moment sensor using carbon fiber plates was developed. The proposed method efficiently removes the anisotropic sensitivity error and decreases the stylus deformation and the actual contact point estimation errors that are major error components of shape measurement using touch probes. The relationship between the measuring force and estimation accuracy of the actual contact point error and stylus deformation error are examined for practical use of the proposed method. The appropriate measuring force condition is presented for the precision measurement.

Effects of initial conditions in operational modal analysis

SUMMARY In this study, the effects of high-amplitude initial conditions on the accuracy of modal parameters, identified from output-only vibration data, are investigated. The influence on the sample output correlation function, which is the basis of most time-domain operational modal analysis techniques, is analyzed first. Then, a numerical simulation is performed to quantify the effect of nonzero initial conditions on the relative accuracy of natural frequencies, damping ratios, and mode shapes. It is shown that, when all identification assumptions are satisfied, high-amplitude initial conditions can significantly reduce the estimation errors, especially for short data records. Finally, a full-scale application is presented where the modal parameters of a six-span high-speed railway bridge are determined from output-only data. The results obtained with two different data sets are compared: The first one consists of the bridge's response to ambient data only, whereas the second one also contains the free vibration recorded immediately after a train passage. Although for most modes the results are similar, it is possible to identify some additional bending and torsion modes from the free vibration data with good accuracy. Copyright © 2013 John Wiley & Sons, Ltd.

Experimental Analysis of the Effect of Cutting Conditions on Microgeometry of the Machined Surface

Machining belongs to the basic and permanent manufacturing technology also on the present time, despite there was an idea (theoretical considering) in the publications of many experts in moulding and casting at the turn of the 70th and 80 years, that the machining could be replaced for the most part by accurate methods of casting or moulding. Although the material losses have been reduced in recent years due to approaching of components' size prepared by moulding or casting to the size desired by technical drawing, it is not possible to achieve the required accuracy of dimensions and shapes. The paper deals with statistical methods application to the evaluation of the maximum height surface roughness profile Rz and mean height surface roughness profile Ra in relation to the feed, cutting speed and depth of cut in longitudinal turning of steel C45. The main part of the paper is to demonstrate the procedure of statistical processing of experimentally obtained data in order to create a prediction model and compare it with the theoretical calculation formulas.

On the Use of Simulated Field-Evaporated Specimen Apex Shapes in Atom Probe Tomography Data Reconstruction

The ability to accurately reconstruct original spatial positions of field-evaporated ions emitted from a surface is fundamental to the success of atom probe tomography. As such, a clear understanding of the evolution of specimen shape and the resultant ions' trajectories during field evaporation plays an important role in improving reconstruction accuracy. To further this understanding, field-evaporation simulations of a bilayer specimen composed of two materials having an evaporation field difference of 20% were performed. The simulated field-evaporation patterns qualitatively compare favorably with experimental data, which provides confidence in the accuracy of specimen shapes predicted by the simulation. Correlations of known original atom positions with detector hit positions as a function of lateral detector position and evaporated depth were derived from the simulation. These correlations are contrasted with the current state-of-the-art reconstruction method thus outlining limitations of the current methodology. A pair of transformations are defined that take into account field-evaporated specimen shapes, and the resulting radial magnifications, to relate recorded ion positions in detector space to reconstructed atomic positions in specimen space. This novel process, when applied to simulated data, results in approximately a factor of 2 improvement in accuracy for reconstructions of interfaces with unequal fields (most general interfaces). This method is not constrained by the fundamental assumption of a hemispherical specimen shape.