圆弧逼近加工椭圆曲线轮廓宏程序的编制

以椭圆曲线轮廓的加工为例,分析了逼近圆弧半径的选取方法,编制了圆弧逼近加工椭圆曲线轮廓的用户宏程序。结果表明,相同条件下,圆弧逼近加工可获得更高的精度和表面质量。     

基于FANUC Oi系统的椭圆轮廓加工通用宏程序编制

介绍了一种运用等步距法结合旋转变换矩阵逼近加工椭圆轮廓的通用宏程序编程方法.较详细地阐述了节点计算和旋转变换矩阵公式,编写出了适用于任意角度放置的椭圆轮廓和椭圆倒角加工的通用宏程序.为类似公式曲线的加工编程提供了一种可供借鉴的方法.     

宏程序在非圆曲线内轮廓加工中的应用

提出了非圆曲线内轮廓加工宏程序编程方法,以非圆曲线内轮廓椭圆为例,分析了内轮廓椭圆宏程序编制流程和刀具轨迹,应用宏程序的循环语句编制了内轮廓椭圆宏程序,为解决数控车削非圆曲线内轮廓加工技术难的问题提供了参考依据。     

数控加工中基于自由曲面表面特性的刀具路径安排

目前CNC上的轨迹控制功能仍主要是直线和圆弧插补,因此当加工自由曲面时,大多只能采用直线或圆弧逼近算法来对曲线进行逼近处理。针对数控加工的实际需求,现在数控系统技术人员对数控机床插补器进行研究并开发出了许多曲线和曲面插补功能。基于曲线插补,在保持进给速度尽可能恒定的条件下,对刀位路径和刀位速度进行离线的曲线拟合,以便于得到用于数控加工的刀位文件。这种方法能有效解决进给速度的波动问题,并能有效压缩刀位文件。为此,提出几种算法来拟合刀位路径和刀位速度轮廓曲线。曲线和曲面插补在数控代码数据量和逼近误差方面都有较大的改善。     

数控车加工非圆曲线编程探讨

数控车床加工方程曲线轮廓，使用G代码不能满足要求，特别是对非圆曲线圆曲线轮廓的加工，必须使用宏程序进行编程，本文主要是通过对数控车非圆曲线的分析探讨，拟合成经验公式来进行数控加工。     

非圆曲线的等误差直线逼近

探讨在数控机床上加工非圆曲线轮廓的等误差直线逼近算法。     

非圆曲线轮廓零件的数控车削加工

运用数控车床加工非圆曲线轮廓零件是数控车床手工编程的难题。以典型非圆曲线轮廓零件为研究对象,分析了用户宏程序的编程方法,编制出了正确的数控加工程序。实践验证表明,宏程序不仅非常简洁而且逻辑严密、通用性好,能够保证非圆曲线轮廓表面加工精度。     

基于进给速度敏感点识别的NURBS曲线平滑插补算法研究

提出了一种基于进给速度敏感点识别的NURBS曲线插补算法,该方法对于兼容NURBS形式的高档数控系统至关重要。粗插补计算造成的轮廓误差与插补经过该点时的进给速度大小有关,敏感点则可根据插补微段逼近时的弓高误差来界定。进而,根据相邻敏感点之间的距离,通过增设安全缓冲区等方法,进行速度曲线自适应规划。整体进给速度曲线可以由各部分进给速度曲线连接而成。为评价算法的有效性,采用3次NURBS曲线在三种不同进给速度指令下进行仿真计算。仿真结果证明,该算法很好地将轮廓精度和进给速度的平滑性进行了系统考虑,能在相邻危险点复杂分布的情况下执行柔性的插补控制。     

加工正弦函数曲线轮廓的插补计算精度分析与编程

对于加工正弦函数曲线轮廓,一般要采用直线段逼近或圆弧段逼近的方法来实现加工。本文从逼近节点的计算和逼近的误差对比角度出发,分析了逼近方法及编程。     

基于VB的非圆曲线轮廓等误差加工的数控编程

用数控机床对非圆曲线轮廓进行加工时,为了控制加工误差,获得较好的表面品质,需要在数控编程时用一定的算法进行节点坐标的计算,而节点坐标的计算是数控编程数值计算中最烦琐、最复杂的部分。设计了非曲线轮廓等误差加工时节点坐标的算法,利用VB语言程序格式,以椭圆轮廓的等误差拟合为例,实现了对该算法的计算机编程并进行了曲线图形仿真,给出了VB程序与用户宏程序的转换关系及相关程序。     

近似度加权平均插值的机器人精度补偿方法研究

为实现物流包装的身份和受潮信息双重检测,设计了一种新型的低成本无芯片RFID湿度传感器,使用电耦合LC谐振器(ELC谐振器)作为湿度传感器监测目标环境相对湿度、U型环谐振器作为无芯片编码结构识别目标身份。通过射频仿真软件HFSS研究谐振器结构参数与谐振频率的关系,获得相应拟合公式,为结构参数设计提供理论依据,并在此基础上设计了8位编码结构;系统研究不同质量分数的聚乙烯醇(PVA)溶液对湿度传感器感湿灵敏度和感湿范围的影响,研制出8位无芯片RFID湿度传感器。根据散射参量提取法获得了U型环谐振器的有效电磁参数,表明其具有超材料属性。所研究的湿度传感器具有感湿灵敏度高、编码容量大、结构简单等优点,有望在智能包装领域得到应用。     

Proportional damping approximation using the energy gain and simultaneous perturbation stochastic approximation

The design of vector second-order linear systems for accurate proportional damping approximation is addressed. For this purpose an error system is defined using the difference between the generalized coordinates of the non-proportionally damped system and its proportionally damped approximation in modal space. The accuracy of the approximation is characterized using the energy gain of the error system and the design problem is formulated as selecting parameters of the non-proportionally damped system to ensure that this gain is sufficiently small. An efficient algorithm that combines linear matrix inequalities and simultaneous perturbation stochastic approximation is developed to solve the problem and examples of its application to tensegrity structures design are presented.     

Precision of stereological planar area predictors

Total planar area can be estimated based on sampling by a lattice of figures (e.g. point patterns, line segments, quadrats). General formulae are provided for the approximation of mean squared errors. The approximation formulae are products of the boundary length and of a parameter that depends only on the sampling scheme. An R package is provided by the authors for the numerical computation of the mean squared error formulae. The speed of convergence of the mean squared error approximation is assessed on the basis of several simulations. Several sampling schemes are compared in view of the approximated mean squared errors.     

非圆曲线的双圆弧拟合及数控加工的程序编制

采用双圆弧逼近的方法,在允许加工误差下解决对于给定的任意非圆曲线的拟合问题。开发并且实现了一个针对非圆弧曲线的数控编程软件工具,其主要功能可以实现对任意给定的非圆曲线的双圆弧拟合及数控加工代码的生成。     

A method for assessing geometrical errors in layered manufacturing. Part 1: Error interaction and transfer mechanisms

Geometric accuracy of components is one of the most important quality characteristics in layered manufacturing processes on which most rapid prototyping (RP) techniques are based. Layered manufacturing is an approximate fabricating process in which the final geometric error of the physical part is affected, not only by the approximation technique used, but also by the fabrication process. Errors that occur in one layer could propagate and transfer to other layers causing an accumulated error effect in the process. In this paper, a concept of disturbance error is introduced to describe the effect of accumulated errors in the fabrication process. A physical model is presented to describe error interactions and error transfer mechanisms in the layered manufacturing process. A geometrical model is developed using surface approximation techniques to describe the relationships of the geometrical errors. It is shown that although the complexity of the part geometry is not directly related to the manufacturing process, it will affect the geometrical errors of the part produced.     

具有线性输出的仪表转动导杆机构的计算机辅助尺度综合

将自动化仪表中实现线性输出的六杆导杆机构转化为基础转动导杆机构,应用经典的机构近似综合理论与现代的误差理论,建立了速度逼近常数的数学模型,讨论了主要机械参数存在区域及对运动、动力性能的影响,分析了传动比理论误差,提出了系统完善的计算机辅助尺度综合的步骤与方法。以线图的形式提供了这类设计问题所需初始值的全部信息,使迭代法设计过程在微机上得以实施,运算收敛快,而最佳一致逼近法求解的机构则保证在逼近区间误差最小。     

非渐开线插齿刀侧齿面的逼近加工──展成磨齿法

本文对非渐开线插齿刀侧齿面的逼近加工进行了分析和研究，提出了用展成磨齿法加工非渐开线插齿刀侧齿面的计算方法，并对砂轮轴截面形状的逼近误差进行了计算。     

基于粒子群优化算法的自由曲线双圆弧逼近

针对数控加工中常用大量直线段逼近平面自由曲线,刀具路径在误差、光顺性、程序数量等方面存在的问题,给出了基于粒子群优化算法的双圆弧逼近平面自由曲线方法。建立了优化的数学模型,并通过最大逼近误差和最大圆弧长度两个变量构造了适应度函数。使用粒子群优化算法确定双圆弧的节点,以达到逼近误差最小、圆弧数量最少的目标,进而对整条曲线的逼近进行优化。进行了试验设计,并与其他方法进行了比较,研究结果证实了方法的有效性与优越性。     

Constrained H2 approximation of multiple input-output delay systems using genetic algorithm

The paper presents a constrained H2 approximation method for multiple input-output delay systems by using a genetic algorithm. The H2 error between the original and the approximate models is minimized subject to constraints on the H(infinity) error between them and the matching of their steady-state under step inputs. In particular, the H2 error is used as the objective (fitness) function for minimization with the best parameters of the approximate model obtained by repeating the genetic operations on the population incorporated a parameter search space expansion scheme. The effectiveness of the proposed method is demonstrated by numerical examples. It is shown that the approximate models obtained by this approach have better approximation performance in both the H2 and H(infinity) norms, as well as the steady-state response, than those obtained by a previous gradient-based minimization approach.     

Choice of the Nominal Transformation Function for a Gamma-Absorption Densimeter under Increased Detector Loadings

The nominal transformation function proposed for a gamma-absorption densimeter under increased detector loadings makes it possible to reduce the systematic error (approximation error) by 4–5 times as compared with the exponential function used in practice. Mathematical relations and techniques of calculating the coefficients of the function which enable us to describe the function using three points of the approximation segment (range) and a set of experimental data by means of the least-squares method are given. It is shown theoretically that in choosing the detector regime it is necessary to restrict our attention to increased loadings with the portion of counting errors not greater than 1/3.