scholarly journals Research on the Novel Hardware Configuration Methods of the Contact R-test Based on the Constraint Models

2021 ◽  
Author(s):  
Yongbing Zhou ◽  
Guofu Ding ◽  
Yuexinkai Zhang ◽  
Lei Jiang
Keyword(s):  
Performance Optimization ◽  
Variable Parameter ◽  
Measurement Model ◽  
Parameter Method ◽  
Calibration Model ◽  
Accuracy Evaluation ◽  
The Novel ◽  
Hardware Configuration ◽  
Measuring Machine ◽  
Five Axis

Abstract R-test is widely used to measure the rotary axis error of five-axis machine tools due to its high accuracy and convenient. There are some deficiencies in the research on measurement performance optimization such as the customized design under certain requirements. The novel hardware configuration methods of the contact R-test are proposed in this paper to realize customization. Firstly, the theoretical measurement model and the calibration model are established to be used as the measurement accuracy evaluation model. Secondly, the influence of hardware parameters on the measurement performance indexes of the measurement system is analyzed and the corresponding constraint models for measurement performance are established. Thirdly, the optimal configuration methods of hardware parameters based on constraint models are proposed using exhaustive search method and variable parameter method respectively . Finally, a prototype that is configured with the hardware parameters based on the above configuration methods, is developed to calibrate on the Coordinate Measuring Machine(CMM) and complete the measurement performance evaluation. The evaluation results show that the hardware configuration methods meet the certain measurement requirements without range and precision waste. The proposed methods provide guidance and reference for the customized design of contact R-test.

scholarly journals Study of Machining of Gears with Regular and Modified Outline Using CNC Machine Tools

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2913
Author(s):  
Rafał Gołębski ◽  
Piotr Boral
Keyword(s):  
Machine Tools ◽  
Coordinate Measuring Machine ◽  
Optical Microscope ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Milling ◽  
Cnc Machine ◽  
Cylindrical Gears ◽  
Measuring Machine ◽  
Five Axis

Classic methods of machining cylindrical gears, such as hobbing or circumferential chiseling, require the use of expensive special machine tools and dedicated tools, which makes production unprofitable, especially in small and medium series. Today, special attention is paid to the technology of making gears using universal CNC (computer numerical control) machine tools with standard cheap tools. On the basis of the presented mathematical model, a software was developed to generate a code that controls a machine tool for machining cylindrical gears with straight and modified tooth line using the multipass method. Made of steel 16MnCr5, gear wheels with a straight tooth line and with a longitudinally modified convex-convex tooth line were machined on a five-axis CNC milling machine DMG MORI CMX50U, using solid carbide milling cutters (cylindrical and ball end) for processing. The manufactured gears were inspected on a ZEISS coordinate measuring machine, using the software Gear Pro Involute. The conformity of the outline, the tooth line, and the gear pitch were assessed. The side surfaces of the teeth after machining according to the planned strategy were also assessed; the tests were carried out using the optical microscope Alicona Infinite Focus G5 and the contact profilographometer Taylor Hobson, Talysurf 120. The presented method is able to provide a very good quality of machined gears in relation to competing methods. The great advantage of this method is the use of a tool that is not geometrically related to the shape of the machined gear profile, which allows the production of cylindrical gears with a tooth and profile line other than the standard.

Error Analysis by Square 3 x 3 Machining Method for Five-Axis Machining Centers

2020 ◽  
Author(s):  
Shigehiko Sakamoto ◽  
Atsushi Yokoyama ◽  
Kazumasa Nakayasu ◽  
Toshihiro Suzuki ◽  
Shinji Koike
Keyword(s):  
International Standards ◽  
Test Method ◽  
Accuracy Evaluation ◽  
Alignment Error ◽  
Machined Surface ◽  
Machining Center ◽  
Alignment Errors ◽  
Assembly Error ◽  
Five Axis ◽  
Machined Surfaces

Abstract The establishment of international standards for 5-axis control machining centers has been supported by the high interest of each country. Internationally, various accuracy inspection methods have been proposed and widely discussed. Accuracy measuring devices for these purposes have also been proposed. In 2014, inspection methods for 5-axis machines were published in ISO 10791-6 and 10791-7. In this research, we propose a test method to process 9 square faces as a new accuracy evaluation method. We simulate the influence of assembly error by the proposed square 3 × 3 machining method on the machined surface. By processing 9 square faces with different tool angle on the same plane, it was possible to evaluate the influence of assembly errors in the 5-axis machining center on the machined surface. Nine surfaces machined by the square 3 × 3 processing method cause differences in surface height due to alignment errors. In addition, nine machined surfaces become all diagonal not parallelism. The alignment errors of the 5-axis machining center is identified by evaluating the orientation of the machined surfaces. Specifically, we propose a newly method to measure the height difference of nine surfaces. Then, the possibility of identifying the alignment error of the 5-axis machining center using the measurement results is shown.

A Complete, Continuous, and Minimal Product of Exponentials-Based Model for Five-Axis Machine Tools Calibration With a Single Laser Tracker, an R-Test, or a Double Ball-Bar

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Peng Xu ◽  
Benny C. F. Cheung ◽  
Bing Li
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Rigid Bodies ◽  
Error Model ◽  
Laser Tracker ◽  
Calibration Model ◽  
Transformation Matrices ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Five Axis

Calibration is an important way to improve and guarantee the accuracy of machine tools. This paper presents a systematic approach for position independent geometric errors (PIGEs) calibration of five-axis machine tools based on the product of exponentials (POE) formula. Instead of using 4 × 4 homogeneous transformation matrices (HTMs), it establishes the error model by transforming the 6 × 1 error vectors of rigid bodies between different frames resorting to 6 × 6 adjoint transformation matrices. A stable and efficient error model for the iterative identification of PIGEs should satisfy the requirements of completeness, continuity, and minimality. Since the POE-based error models for five-axis machine tools calibration are naturally complete and continuous, the key issue is to ensure the minimality by eliminating the redundant parameters. Three kinds of redundant parameters, which are caused by joint symmetry information, tool-workpiece metrology, and incomplete measuring data, are illustrated and explained in a geometrically intuitive way. Hence, a straightforward process is presented to select the complete and minimal set of PIGEs for five-axis machine tools. Based on the established unified and compact error Jacobian matrices, observability analyses which quantitatively describe the identification efficiency are conducted and compared for different kinds of tool tip deviations obtained from several commonly used measuring devices, including the laser tracker, R-test, and double ball-bar. Simulations are conducted on a five-axis machine tool to illustrate the application of the calibration model. The effectiveness of the model is also verified by experiments on a five-axis machine tool by using a double ball-bar.

Vibration Performance Optimization of the Semi-Active Suspension with Fuzzy Control Method

2012 ◽  
Vol 468-471 ◽  
pp. 1123-1127
Author(s):  
Jin Ning Zhi ◽  
Jian Wei Yang ◽  
Jun Zhe Dong
Keyword(s):  
Fuzzy Control ◽  
Dynamic Load ◽  
Performance Optimization ◽  
Ride Comfort ◽  
Control Method ◽  
Heavy Vehicle ◽  
Variable Universe ◽  
Suspension Parameters ◽  
Variable Universe Fuzzy Control ◽  
Five Axis

In order to improve the dynamic performance of five-axis heavy vehicle, a variable universe fuzzy control method is proposed to optimize suspension parameters. Five-axis multi-body dynamic model including electro-hydraulic proportional valve was firstly established in software ADAMS/Car. The variable universe fuzzy controller based on fuzzy neural network was also designed in MATLAB/Simulink, and then the co-simulation was conducted. The dynamic characteristics of five-axis heavy vehicle are studied to verify the effect of suspension parameters optimized by variable universe fuzzy control method in the A, B and C-level random pavement and different speed conditions. Simulation results show that compared with passive suspension, the real-time optimization of variable fuzzy control based on FNN can improve the ride comfort and the dynamic load of tire. Under different driving conditions, ride comfort can be increased by about 25%-30%, and the dynamic load of tire generally decreases by 25%-35%. Therefore this method has a certain practicability and effectiveness.

scholarly journals A mechanism for balancing accuracy and scope in cross-machine black-box GPU performance modeling

2020 ◽  
Vol 34 (6) ◽  
pp. 589-614
Author(s):  
James D Stevens ◽  
Andreas Klöckner
Keyword(s):  
Performance Optimization ◽  
Heterogeneous Computing ◽  
Performance Modeling ◽  
Matrix Multiplication ◽  
Black Box ◽  
Ease Of Use ◽  
Performance Tuning ◽  
Parallel Applications ◽  
Accuracy Evaluation ◽  
Trade Offs

The ability to model, analyze, and predict execution time of computations is an important building block that supports numerous efforts, such as load balancing, benchmarking, job scheduling, developer-guided performance optimization, and the automation of performance tuning for high performance, parallel applications. In today’s increasingly heterogeneous computing environment, this task must be accomplished efficiently across multiple architectures, including massively parallel coprocessors like GPUs, which are increasingly prevalent in the world’s fastest supercomputers. To address this challenge, we present an approach for constructing customizable, cross-machine performance models for GPU kernels, including a mechanism to automatically and symbolically gather performance-relevant kernel operation counts, a tool for formulating mathematical models using these counts, and a customizable parameterized collection of benchmark kernels used to calibrate models to GPUs in a black-box fashion. With this approach, we empower the user to manage trade-offs between model accuracy, evaluation speed, and generalizability. A user can define their own model and customize the calibration process, making it as simple or complex as desired, and as application-targeted or general as desired. As application examples of our approach, we demonstrate both linear and nonlinear models; these examples are designed to predict execution times for multiple variants of a particular computation: two matrix-matrix multiplication variants, four discontinuous Galerkin differentiation operation variants, and two 2D five-point finite difference stencil variants. For each variant, we present accuracy results on GPUs from multiple vendors and hardware generations. We view this highly user-customizable approach as a response to a central question arising in GPU performance modeling: how can we model GPU performance in a cost-explanatory fashion while maintaining accuracy, evaluation speed, portability, and ease of use, an attribute we believe precludes approaches requiring manual collection of kernel or hardware statistics.

scholarly journals Linear Accuracy of Full-Arch Digital Models Using Four Different Scanning Methods: An In Vitro Study Using a Coordinate Measuring Machine

2020 ◽  
Vol 10 (8) ◽  
pp. 2741 ◽  
Author(s):  
Young Hyun Kim ◽  
Sang-Sun Han ◽  
Yoon Joo Choi ◽  
Chang-Woo Woo
Keyword(s):  
Coordinate Measuring Machine ◽  
In Vitro Study ◽  
Dental Arch ◽  
Accuracy Evaluation ◽  
Arch Model ◽  
Linear Measurements ◽  
Scanning Method ◽  
True Model ◽  
Measuring Machine

Improving the accuracy of the digital model is essential for the digitalization of the dental field. This study introduced a novel method of objective accuracy evaluation of digitized full dental arch model using coordinate measuring machine (CMM). To obtain a true linear measurement value using the CMM, 17 reference balls were attached to the typodont, and 12 measurements between balls on the X-(width), Y-(length), and Z-axes (height) were performed automatically. A rubber impression and a plaster cast replica of the typodont with balls were fabricated, and they were digitized with following methods: (a) true model intraoral scans; (b) impression cone-beam computed tomography (CBCT) scans; (c) cast CBCT scans; and (d) cast extraoral scans. Each scanning method was performed 20 times. Twelve linear measurements on the digitized models were automatically made using software. The one-sample t-test and one-way analysis of variance were used for measurement accuracy analysis. The cast extraoral scan was most accurate on X- and Y-axes, while impression CBCT was the most accurate on Z-axis. Over all axes, the intraoral scan resulted in the most deviation from the true model, and the reproducibility of each scan was also low. Extraoral scan shows high precision on width and length, and impression CBCT is advantageous for dental work where height factor is of importance.

scholarly journals Segmental Modification of the Mualem Model by Remolded Loess

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Le-fan Wang ◽  
Xing-zhong Weng ◽  
Zhi-hua Yao ◽  
Ren-yi Zhang ◽  
Wan Li ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Linear Relation ◽  
Goodness Of Fit ◽  
Characteristic Curve ◽  
Variable Parameter ◽  
Dry Density ◽  
Parameter Method ◽  
Test Results ◽  
Segmentation Method ◽  
Through Diffusion

The measured diffusion coefficient and soil-water characteristic curve (SWCC) of remolded loess were used to modify the Mualem model for increasing its accuracy. The obtained results show that the goodness of fit between the Mualem model and the variable parameter-modified Mualem method comparing with the test results was not high. The saturation of 0.65 was introduced as the boundary to divide the curve of the measured diffusion coefficient into two segments. When the segmentation method combined with the variable parameter method was used to modify the Mualem model, the fitting correlation coefficient was increased to 0.921–0.998. The modified parameters Ko and L corresponding to remolded loess were calculated for different dry densities. Based on the exponential function between Ko and dry density and the linear relation between L and dry density, the segmentally modified Mualem model was established for remolded loess by considering variation in dry density. The results of the study can be used for directly determining the unsaturated infiltration coefficient and for indirectly determining the SWCC through diffusion coefficient.

scholarly journals G-NETWORKS AND THEIR APPLICATIONS TO MACHINE LEARNING, ENERGY PACKET NETWORKS AND ROUTING: INTRODUCTION TO THE SPECIAL ISSUE

2017 ◽  
Vol 31 (4) ◽  
pp. 381-395 ◽  
Author(s):  
Mehmet Ufuk Caglayan
Keyword(s):  
Machine Learning ◽  
Performance Optimization ◽  
Saint Paul ◽  
Network Routing ◽  
Packet Networks ◽  
The Novel ◽  
Special Issue ◽  
Research Directions ◽  
Cloud Management ◽  
Theoretical Developments

This paper introduces a special issue of this journal (Probability in the Engineering and Informational Sciences) that is devoted to G(elenbe)-Networks and their Applications. The special issue is based on revised versions of some of the papers that were presented at a workshop held in early January 2017 at the Séminaire Saint-Paul in Nice (France). It includes contributions in several research directions that followed from the introduction of the G-Network in the late 1980s. The papers present original theoretical developments, as well as applications of G-Networks to Machine Learning, to the performance optimization of energy systems via the novelEnergy Packet Networksformalism for systems that operate with renewable and intermittent energy sources, and to packet network routing and Cloud management over the Internet. We introduce these contributions from the perspective of an overview of recent work based on G-Networks.

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