Acoustic waves in the pseudo-triaxial experiment system experience refraction phenomena.The conventional assumption that acoustic waves propagate along a straight line in traditional methods can lead to significant er...Acoustic waves in the pseudo-triaxial experiment system experience refraction phenomena.The conventional assumption that acoustic waves propagate along a straight line in traditional methods can lead to significant errors in localization results.To the end,this paper presents a method for locating acoustic emission(AE)sources in pseudo-triaxial experiments using shortest paths and orthogonal constraints.The approach consists of three main steps:(1)establishing control equations for refraction paths from AE sources to sensor locations;(2)calculating refraction point locations using the shortest travel principle and orthogonal constraints;(3)determining source coordinates using Taylor's first-order expansion.The results from laboratory AE experiments demonstrate that the average localization accuracy of the new method is only 6.5 mm,which is 66%more precise than the accuracy(19.4 mm)of the traditional method.Furthermore,simulation results indicate that the new method is not affected by the refraction ratio of the media and maintains the highest positioning accuracy across various arrival and velocity errors.展开更多
Existing curve fitting algorithms of NC machining path mainly focus on the control of fitting error,but ignore the problem that the original discrete cutter position points are not enough in the high curvature area of...Existing curve fitting algorithms of NC machining path mainly focus on the control of fitting error,but ignore the problem that the original discrete cutter position points are not enough in the high curvature area of the tool path.It may cause a sudden change in the drive force of the feed axis,resulting in a large fluctuation in the feed speed.This paper proposes a new non-uniform rational B-spline(NURBS)curve fitting optimization method based on curvature smoothing preset point constraints.First,the short line segments generated by the CAM software are optimally divided into different segment regions,and then the curvature of the short line segments in each region is adjusted to make it smoother.Secondly,a set of characteristic points reflecting the change of the curvature of the fitted curve is constructed as the control apex of the fitted curve,and the curve is fitted using the NURBS curve fitting optimization method based on the curvature smoothing preset point constraint.Finally,the curve fitting error and curve volatility are analyzed with an example,which verifies that the method can significantly improve the curvature smoothness of the high-curvature tool path,reduce the fitting error,and improve the feed speed.展开更多
This paper considers dealing with path constraints in the framework of the improved control vector iteration （CVI） approach. Two available ways for enforcing equality path constraints are presented, which can be dir...This paper considers dealing with path constraints in the framework of the improved control vector iteration （CVI） approach. Two available ways for enforcing equality path constraints are presented, which can be directly incorporated into the improved CVI approach. Inequality path constraints are much more difficult to deal with, even for small scale problems, because the time intervals where the inequality path constraints are active are unknown in advance. To overcome the challenge, the ll penalty function and a novel smoothing technique are in-troduced, leading to a new effective approach. Moreover, on the basis of the relevant theorems, a numerical algo-rithm is proposed for nonlinear dynamic optimization problems with inequality path constraints. Results obtained from the classic batch reaCtor operation problem are in agreement with the literature reoorts, and the comoutational efficiency is also high.展开更多
离轴非球面形状不对称且其表面曲率变化非线性,给面形高精度测量带来挑战。为解决现有离轴非球面面形测量方法高度依赖待测件初始调整位姿和曲率变化难适应的问题,本文提出了一种基于空间约束的差动共焦离轴非球面自适应测量方法,以实...离轴非球面形状不对称且其表面曲率变化非线性,给面形高精度测量带来挑战。为解决现有离轴非球面面形测量方法高度依赖待测件初始调整位姿和曲率变化难适应的问题,本文提出了一种基于空间约束的差动共焦离轴非球面自适应测量方法,以实现对离轴非球面的无初始位姿依赖、曲率变化自适应、高精度测量。首先,根据平移-回转扫描测量原理和差动共焦技术抗表面倾角精准定焦的性能,从规划测量点和待测点之间的距离和倾角两个维度出发,构建了空间约束模型,基于该模型,对等面积准则下的螺旋扫描路径规划算法进行优化,实现对离轴非球面测量路径的曲率自适应动态调整。使用该方法对离轴非球面和20°倾斜平面进行测量实验,将测量结果与Zygo干涉仪的测量结果点对点作差,面形差别的均方根(Root Mean Square,RMS)值均优于10 nm,对应3σ优于5 nm,满足离轴非球面的高精度测量要求。展开更多
基金the financial support provided by the National Key Research and Development Program for Young Scientists(Grant No.2021YFC2900400)the National Natural Science Foundation of China(Grant No.52304123)the China Postdoctoral Science Foundation(Grant No.2023M730412).
文摘Acoustic waves in the pseudo-triaxial experiment system experience refraction phenomena.The conventional assumption that acoustic waves propagate along a straight line in traditional methods can lead to significant errors in localization results.To the end,this paper presents a method for locating acoustic emission(AE)sources in pseudo-triaxial experiments using shortest paths and orthogonal constraints.The approach consists of three main steps:(1)establishing control equations for refraction paths from AE sources to sensor locations;(2)calculating refraction point locations using the shortest travel principle and orthogonal constraints;(3)determining source coordinates using Taylor's first-order expansion.The results from laboratory AE experiments demonstrate that the average localization accuracy of the new method is only 6.5 mm,which is 66%more precise than the accuracy(19.4 mm)of the traditional method.Furthermore,simulation results indicate that the new method is not affected by the refraction ratio of the media and maintains the highest positioning accuracy across various arrival and velocity errors.
基金the Open Foundation Project of Jiangsu Key Laboratory of Precision and Micro-manufacturing Technology Open Fund Project.
文摘Existing curve fitting algorithms of NC machining path mainly focus on the control of fitting error,but ignore the problem that the original discrete cutter position points are not enough in the high curvature area of the tool path.It may cause a sudden change in the drive force of the feed axis,resulting in a large fluctuation in the feed speed.This paper proposes a new non-uniform rational B-spline(NURBS)curve fitting optimization method based on curvature smoothing preset point constraints.First,the short line segments generated by the CAM software are optimally divided into different segment regions,and then the curvature of the short line segments in each region is adjusted to make it smoother.Secondly,a set of characteristic points reflecting the change of the curvature of the fitted curve is constructed as the control apex of the fitted curve,and the curve is fitted using the NURBS curve fitting optimization method based on the curvature smoothing preset point constraint.Finally,the curve fitting error and curve volatility are analyzed with an example,which verifies that the method can significantly improve the curvature smoothness of the high-curvature tool path,reduce the fitting error,and improve the feed speed.
基金Supported by the National Natural Science Foundation of China(U1162130)the National High Technology Research and Development Program of China(2006AA05Z226)Outstanding Youth Science Foundation of Zhejiang Province(R4100133)
文摘This paper considers dealing with path constraints in the framework of the improved control vector iteration （CVI） approach. Two available ways for enforcing equality path constraints are presented, which can be directly incorporated into the improved CVI approach. Inequality path constraints are much more difficult to deal with, even for small scale problems, because the time intervals where the inequality path constraints are active are unknown in advance. To overcome the challenge, the ll penalty function and a novel smoothing technique are in-troduced, leading to a new effective approach. Moreover, on the basis of the relevant theorems, a numerical algo-rithm is proposed for nonlinear dynamic optimization problems with inequality path constraints. Results obtained from the classic batch reaCtor operation problem are in agreement with the literature reoorts, and the comoutational efficiency is also high.
文摘离轴非球面形状不对称且其表面曲率变化非线性,给面形高精度测量带来挑战。为解决现有离轴非球面面形测量方法高度依赖待测件初始调整位姿和曲率变化难适应的问题,本文提出了一种基于空间约束的差动共焦离轴非球面自适应测量方法,以实现对离轴非球面的无初始位姿依赖、曲率变化自适应、高精度测量。首先,根据平移-回转扫描测量原理和差动共焦技术抗表面倾角精准定焦的性能,从规划测量点和待测点之间的距离和倾角两个维度出发,构建了空间约束模型,基于该模型,对等面积准则下的螺旋扫描路径规划算法进行优化,实现对离轴非球面测量路径的曲率自适应动态调整。使用该方法对离轴非球面和20°倾斜平面进行测量实验,将测量结果与Zygo干涉仪的测量结果点对点作差,面形差别的均方根(Root Mean Square,RMS)值均优于10 nm,对应3σ优于5 nm,满足离轴非球面的高精度测量要求。
