Evaluation of Deviation Zone Based on Maximum Conformance to Tolerances

2011 ◽  
Author(s):  
Ahmad Barari
Keyword(s):  
Closed Loop ◽  
Evaluation Process ◽  
Accurate Estimation ◽  
Tolerance Zone ◽  
Coordinate Metrology ◽  
Inspection Process ◽  
Geometric Deviations ◽  
The Given ◽  
Best Fit ◽  
Deviation Zone

The accurate estimation of the geometric deviations is not possible only by manipulating the Euclidian distances of the discrete measured points from substitute geometry. The real geometric deviations of a measured surface need to be calculated based on the desired tolerance zone of the surface. This fact is usually neglected in common practices in the coordinate metrology of surfaces. The importance of considering the desired tolerance zone in estimation of the optimum deviation zone is demonstrated in this paper. Then a best fit method is presented which complies with the tolerance requirements of the designed surface. The developed fitting methodology constructs a substitute geometry to minimizes the residual deviations corresponding to the given tolerance zone and the needs of down-stream operations that use the results of the inspection process. It is shown how the developed objective function can be adopted for a case of closed-loop manufacturing process, when the under-cut residual deviations of the manufactured part can be corrected by a down-stream operation. In order to validate the proposed methodology, experiments are conducted. The results show a significant reduction of uncertainties in coordinate metrology of geometric surfaces. Implementation of this method directly results in increasing the accuracy of the entire tolerance evaluation process, and less uncertainty in quality control of the manufactured parts.

An Approach to Estimate the Detailed Deviation Zone in Coordinate Metrology Using Harmonic Function Properties

2014 ◽  
Author(s):  
Saeed Jamiolahmadi ◽  
Ahmad Barari
Keyword(s):  
Harmonic Functions ◽  
Closed Loop ◽  
Mean Value ◽  
Manufacturing Processes ◽  
Mean Value Property ◽  
Detailed Understanding ◽  
Manufacturing Errors ◽  
Coordinate Metrology ◽  
Geometric Deviations ◽  
Deviation Zone

Understanding the exact details of deviation zone related to a manufactured surface needs measurement of infinite number of points. Coordinate metrology provides deviation of the limited number of discrete points on a measured surface, but typically it is not capable to explore any information of the surface regions between these measured points. An approach to estimate the Distribution of Geometric Deviations (DGD) on the entire inspected surface is presented in this paper. The methodology is developed based on estimation of mean value property of the harmonic functions and Laplace equation. The resulting DGD model can be employed to estimate the deviation values at any unmeasured point of the inspected surface when a detailed understanding of the surface geometric deviations is required. Implementation of the developed methodology is described and case studies for typical industrial parts are presented. This methodology can be used for closed-loop of inspection and manufacturing processes when a compensation scheme is available to compensate the manufacturing errors based on the DGD model.

scholarly journals Convergence of a finite difference approach for detailed deviation zone estimation in coordinate metrology

ACTA IMEKO ◽  
2015 ◽  
Vol 4 (4) ◽  
pp. 20 ◽  
Author(s):  
Ahmad Barari ◽  
Saeed Jamiolahmadi
Keyword(s):  
Measurement Techniques ◽  
Mean Value ◽  
Sufficient Information ◽  
Mathematical Functions ◽  
Actual Case ◽  
Novel Approach ◽  
Coordinate Metrology ◽  
Geometric Deviations ◽  
Surface Deviation ◽  
Deviation Zone

<p class="Abstract">In order to comprehend an entire surface's deviation zone, infinite measured points are required. Using the common measurement techniques through coordinate metrology, a limited number of surface actual points can be acquired. However, the obtained points would not provide sufficient information to examine the geometry thoroughly. A novel approach to predict surface behaviour via Distribution of Geometric Deviations (DGD) is examined in this paper. The methodology governs the mean value property of the harmonic functions to solve Laplace equation around each measured point. This DGD model can be used to reconstruct surface deviation values at any unmeasured point of the inspected surface based on a limited number of measured points. The convergence of the introduced approach is studied in this paper. A complete approach to implement the developed methodology is described, and the validation process is studied using actual case studies and mathematical functions. This methodology is practical in closed-loop inspection and manufacturing processes to form a scheme for compensating the surface errors during manufacturing process based on the DGD model.</p>

A Finite Element Approach to Estimate the Detailed Deviation Zone in Coordinate Metrology

2015 ◽  
Author(s):  
Amirali Lalehpour ◽  
Ahmad Barari ◽  
Saeed Jamiolahmadi
Keyword(s):  
Finite Element ◽  
Detailed Knowledge ◽  
Finite Element Approach ◽  
Manufacturing Errors ◽  
Coordinate Metrology ◽  
Geometric Deviations ◽  
Element Approach ◽  
Deviation Zone ◽  
Solution Estimates

The exact detailed knowledge of deviation zone in a manufactured surface needs measurement of infinite number of points when the coordinate metrology is utilized. The coordinate metrology process provides deviation of the limited number of discrete points on a measured surface, but typically the process is not capable to explore any information of the surface regions between these measured points. A Finite Element approach for Deviation Zone Evaluation (DZE) on the entire inspected surface is presented in this paper. The developed DZE solution estimates the deviation values at any unmeasured point of the inspected surface when a detailed understanding of the surface geometric deviations is required. Implementation of the developed methodology is described and case study for typical industrial parts is presented. This methodology can be used for closed-loop of inspection and manufacturing processes when a compensation scheme is available to compensate the manufacturing errors based on the DZE data.

Establishing a School-Wide Systematic Closed-Loop Course Evaluation Process to Improve Course and Instructor Effectiveness

2015 ◽  
Vol 27 (5) ◽  
pp. 3-13
Author(s):  
Jacqueline E. McLaughlin ◽  
Amy Sloane ◽  
Elizabeth Billings ◽  
Mary T. Roth
Keyword(s):  
Closed Loop ◽  
Evaluation Process ◽  
Course Evaluation ◽  
Instructor Effectiveness

Cost Analysis and Fuzzy Control for Collapsible Container Usage Based on Closed-Loop Supply Chain Model

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Xinyan Ou ◽  
Jorge Arinez ◽  
Qing Chang ◽  
Guoxian Xiao
Keyword(s):  
Mathematical Model ◽  
Fuzzy Control ◽  
Closed Loop ◽  
Control Method ◽  
Fuzzy Controller ◽  
Accurate Estimation ◽  
Chain Model ◽  
Market Demand ◽  
Total Cost ◽  
Logistic Cost

In the last decade, global competition has forced manufacturers to optimize logistics. The implementation of collapsible containers provides a new perspective for logistics cost savings, since using collapsible containers reduces the frequency of shipping freight. However, optimization of logistic cost is complicated due to the interactions in a system, such as market demand, inventory, production throughput, and uncertainty. Therefore, a systematic model and accurate estimation of the total cost and system performance are of great importance for decision making. In this paper, a mathematical model is developed to describe deterministic and stochastic scenarios for a closed-loop container dynamic flow system. The uncertainties in a factory and a supplier are considered in the model. The performance evaluation of the collapsible container system and total cost estimation are provided through model analysis. Furthermore, fuzzy control method is proposed to monitor the processing rate of the supplier and the factory and to adjust the rate of the supplier operation then further reduce the logistic cost. A case study with a matlab simulation is presented to illustrate the accuracy of the mathematical model and the effectiveness of the fuzzy controller.

Reverse Kinematic Analysis of the Spatial Six Axis Robotic Manipulator With Consecutive Joint Axes Parallel

2007 ◽  
Author(s):  
Javier Rolda´n Mckinley ◽  
Carl Crane ◽  
David B. Dooner
Keyword(s):  
Kinematic Analysis ◽  
Closed Loop ◽  
Degree Of Freedom ◽  
Repetitive Motion ◽  
Spatial Mechanism ◽  
Joint Axis ◽  
Specific Geometry ◽  
Noncircular Gears ◽  
Six Degree Of Freedom ◽  
The Given

This paper introduces a reconfigurable one degree-of-freedom spatial mechanism that can be applied to repetitive motion tasks. The concept is to incorporate five pairs of noncircular gears into a six degree-of-freedom closed-loop spatial chain. The gear pairs are designed based on the given mechanism parameters and the user defined motion specification of a coupler link of the mechanism. It is shown in the paper that planar gear pairs can be used if the spatial closed-loop chain is comprised of six pairs of parallel joint axes, i.e. the first joint axis is parallel to the second, the third is parallel to the fourth, …, and the eleventh is parallel to the twelfth. This paper presents the detailed reverse kinematic analysis of this specific geometry. A numerical example is presented.

scholarly journals Riemannian Means as Solutions of Variational Problems

2006 ◽  
Vol 9 ◽  
pp. 86-103 ◽  
Author(s):  
Luís Machado ◽  
F. Silva Leite ◽  
Knut Hüper
Keyword(s):  
Riemannian Manifold ◽  
Variational Problem ◽  
Lie Groups ◽  
Riemannian Manifolds ◽  
Single Point ◽  
Variational Problems ◽  
Compact Lie Groups ◽  
Data Set ◽  
The Given ◽  
Best Fit

We formulate a variational problem on a Riemannian manifoldMwhose solutions are piecewise smooth geodesies that best fit a given data set of time labelled points inM. By a limiting process, these solutions converge to a single point inM. which we prove to be the Riemannian mean of the given points for some particular Riemannian manifolds such as Euclidean spaces, connected and compact Lie groups, and spheres.

EVALUATION OF CLOSED-LOOP CONTROL SYSTEM FOR RESTORING STANDING AND SITTING FUNCTIONS BY FUNCTIONAL ELECTRICAL STIMULATION

2005 ◽  
Vol 17 (01) ◽  
pp. 19-26 ◽  
Author(s):  
CHENG-LIANG LIU ◽  
CHUNG-HUANG YU ◽  
SHIH-CHING CHEN ◽  
CHANG-HUNG CHEN
Keyword(s):  
Electrical Stimulation ◽  
Functional Electrical Stimulation ◽  
Closed Loop ◽  
Spinal Cord Injuries ◽  
Control Method ◽  
Control Strategies ◽  
Evaluation Process ◽  
Closed Loop Control ◽  
Loop Control ◽  
Loop Control System

Functional electrical stimulation (FES) is a method for restoring the functional movements of paraplegic or patients with spinal cord injuries. However, the selection of parameters that control the restoration of standing up and sitting functions has not been extensively investigated. This work provides a method for choosing the four main items involved in evaluating the strategies for sit-stand-sit movements with the aid of a modified walker. The control method uses the arm-supported force and the angles of the legs as feedback signals to change the intensity of the electrical stimulation of the leg muscles. The control parameters, Ki and Kp, are vary for different control strategies. Four items are collected through questionnaires and used for evaluation. They are the maximum reactions of the two hands, the average reaction of the two hands, largest absolute angular velocity of the knee joints, and the sit-stand-sit duration time. The experimental data are normalized to facilitate comparison. Weighting factors are obtained and analyzed from questionnaires answered by experts and are added to evaluation process for manipulation. The results show that the best strategy is the closed-loop control with parameters Ki=0.5 and Kp=0.

Effective atomic number of Mn–Co–Fe2O3 ternary alloys using the Rayleigh to Compton scattering ratio

2017 ◽  
Vol 95 (4) ◽  
pp. 402-406 ◽  
Author(s):  
M. Büyükyıldız ◽  
M. Kurudirek
Keyword(s):  
Atomic Number ◽  
Effective Atomic Number ◽  
Ternary Alloys ◽  
Interpolation Procedure ◽  
Scattering Ratio ◽  
Relative Differences ◽  
The Given ◽  
Best Fit ◽  
Good Agreement ◽  
Versus Method

The objective of this work is to determine effective atomic number (Zeff) of Fe2O3(0.2)–Mnx–Coy (x + y = 0.8) ternary alloys using scattering of gamma photons and to compare available methods used to calculate Zeff. For this purpose, we have developed a fitting equation using the ratio of Rayleigh (R) to Compton (C) scattering intensity, R/C for the calculation of effective atomic number of ternary alloy (i.e., Mn–Co–Fe2O3). R and C scattering intensities for the given materials have been measured using a mono-energetic beam of 59.54 keV gamma rays and a scattering angle of 130° (x = 4.36 Å−1). The R/C ratios of elements with 20 ≤ Z ≤ 30 were used to constitute the best fit equation. R/C scattering ratios, when plotted as a function of atomic number, results in a fitted equation, which is then used for derivation of Zeff of the alloys. Also, experimental R/C values were used to determine effective atomic number of the alloys by using interpolation procedure. For comparison, Zeff of alloys were also calculated using different methods. Maximum relative differences between Zeff for experimental and theoretical results were found to be ≤8.04% (exp. 1 (fitting) versus method 6) and were found to be ≤8.99% (exp. 2 (interpolation) versus method 7) indicating a good agreement for the chosen alloys.

A Task Driven Approach to the Synthesis of Spherical 4R Linkages Using Algebraic Fitting Method

2013 ◽  
Author(s):  
Ping Zhao ◽  
Xiangyun Li ◽  
Anurag Purwar ◽  
Kartik Thakkar ◽  
Q. J. Ge
Keyword(s):  
Linear Method ◽  
Geometric Constraints ◽  
Motion Generation ◽  
Constraint Manifold ◽  
Fitting Method ◽  
Kinematic Mapping ◽  
Motion Approximation ◽  
The Given ◽  
Best Fit ◽  
Additional Constraints

This paper studies the problem of spherical 4R motion approximation from the viewpoint of extraction of circular geometric constraints from a given set of spherical displacements. This paper extends our planar 4R linkage synthesis work to the spherical case. By utilizing kinematic mapping and quaternions, we map spherical displacements into points and the workspace constraints of the coupler into intersection of algebraic quadrics (called constraint manifold), respectively, in the image space of displacements. The problem of synthesizing a spherical 4R linkage is reduced to finding a pencil of quadrics that best fit the given image points in the least squares sense. Additional constraints on the pencil identify the quadrics that represent a spherical circular constraint. The geometric parameters of the quadrics encode information about the linkage parameters which are readily computed to obtain a spherical 4R linkage that best navigates through the given displacements. The result is an efficient and largely linear method for spherical four-bar motion generation problem.

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