A Study on Localization Accuracy of Fixturing System
Date Issued
2005
Date
2005
Author(s)
Tsai, Yu-Hsiang
DOI
zh-TW
Abstract
This paper presents two analyses, Root Sum of Square (RSS) statistical localization variance analysis and localization accuracy matrix analysis, for the characteristics of localization accuracy of a 2D fixturing system in fixturing planning stage. By using geometric fixturing constraint theory, prismatic workpiece with line or arc segments is fixtured by locators in a unique and accurate position and orientation. The fixturing contact locus analysis is next employed to verify the necessary fixturing condition of 3-point contact. According to the localization variances of the fixturing contact points and the shapes of prismatic workpiece, the translational and rotational position variances of a workpiece can be expressed by the variances of the position errors of locators. RSS statistical localization variance analysis is then utilized to calculate the translational and rotational position variances of a workpiece. Monte Carlo simulation is carried out to verify the obtained results. By using localization accuracy matrix analysis, three principles for evaluating different localization accuracies are obtained, and the position of locators with the best localization accuracy can be found.
From the results of these analyses, some important conclusions are obtained. The normal positional variances of the fixturing contact points for the positional variance of the workpiece are more important than the tangential ones. The localization accuracy matrix analysis provides a quick way to find the position of locators with a minimum localization variance and the best localization accuracy. The translational and rotational position variance of a workpiece are extreme large when the position of locators is near singular point. Different examples are given to justify these methods. The results of these three analyses are consistent with each other.
From the results of these analyses, some important conclusions are obtained. The normal positional variances of the fixturing contact points for the positional variance of the workpiece are more important than the tangential ones. The localization accuracy matrix analysis provides a quick way to find the position of locators with a minimum localization variance and the best localization accuracy. The translational and rotational position variance of a workpiece are extreme large when the position of locators is near singular point. Different examples are given to justify these methods. The results of these three analyses are consistent with each other.
Subjects
蒙地卡羅模擬
定位精度矩陣
均方根統計分析
定位變異量
夾持系統
fixturing system
localization variance
localization accuracy matrix
RSS statistical localization variance analysis
Monte Carlo simulation
Type
thesis
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