Prediction of diameter errors compensation in bars turning

On the basis of analyzing the machine-workpiece-tool system, the main factors affecting diameter errors in bars turning are considered, and the mathematic models of the actual workpiece diameter at the cutting point are established according to the three usual methods of mounting workpieces on a turning machine. Further a predictionsystem for diameter errors is developed; a new method, called discrete nodes output, is presented and applied to expressing workpiece diameter errors at given points along the part axis, then off-line compensation is implemented according to the prediction values to diminish machining errors. The results indicate that the method can diminish diameter errors more than 70%, greatly improve the machining accuracy of bars.     

细长轴加工误差预测与补偿方法研究

在前期对车削加工过程仿真研究的基础上,开发了一套车削加工仿真系统,根据车床本身的运动误差及切削参数,对其加工过程进行仿真,并建立了综合误差模型来预测其加工误差．预测结果与实际的测量值具有较好的一致性．     

Modeling,identification and compensation for geometric errors of laser annealing table简

In order to improve the process precision of an XY laser annealing table, a geometric error modeling, and an identification and compensation method were proposed. Based on multi-body system theory, a geometric error model for the laser annealing table was established. It supports the identification of 7 geometric errors affecting the annealing accuracy. An original identification method was presented to recognize these geometric errors. Positioning errors of 5 lines in the workspace were measured by a laser interferometer, and the 7 geometric errors were identified by the proposed algorithm. Finally, a software-based error compensation method was adopted, and a compensation mechanism was developed in a postprocessor based on LabVIEW. The identified geometric errors can be compensated by converting ideal NC codes to actual NC codes. A validation experiment has been conducted on the laser annealing table, and the results indicate that positioning errors of two validation lines decreased from ±37 μm and ±33 μm to±5 μm and ±4.5 μm, respectively. The geometric error modeling, identification and compensation method presented in this work can be straightforwardly extended to any configurations of 2-dimensional worktable.     

Lag compensation errors in active power filters based on DSP controllers

The growing problems of harmonic pollution on coal mine power lines caused by high-power DC drive systems has increased the use of active power filters. We analyzed compensation errors caused by the time lag in the detecting circuits of an active power filter based on DSP control. We derived a mathematical model for the compensation error starting from the error estimation when a single distortion frequency is present. This model was then extended to the case where multiple frequencies are present in the distortion. A formula for a general theory of compensation error with fixed load and fixed lag time is presented. The theoretical analysis and experimental results show that the delay time of an active power filter mainly arises from the sampling time. Lower sampling frequencies introduce larger compensation errors in the active power filter reference current.     

考虑工件热变形的大型结构件误差建模与补偿

为减少大型结构件的加工误差,基于热特性分析建立了考虑工件热变形的综合误差模型及其补偿方法.分析光栅尺温度变化产生热变形的机理,并通过热流研究光栅尺局部的非线性温度变化规律,对龙门加工中心几何误差和热误差分别建模,并叠加生成复合误差模型.建立工件热变形与温度变化量之间的线性模型,并分析加工过程中复合误差与工件热变形之间的相互关系,建立考虑工件热变形的综合误差模型.利用数控系统外部机械原点偏移功能,应用自主研制的误差实时补偿系统,并依据考虑工件热变形的综合误差模型,实现对龙门加工中心的误差补偿.结果表明:只考虑机床误差时,复合误差模型有很高的预测精度,但并不能应用到有较大工件热变形的大型结构件加工中;而考虑工件热变形的综合误差模型在大型扭力臂的实际加工中效果良好,其加工定位精度至少提高了52%.     

Adaptive compensation of sculptured surface machining errors by open architecture manufacturing system

0　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｍａｃｈｉｎｉｎｇｅｒｒｏｒｓｔｈａｔｇｅｎｅｒａｌｌｙｏｃｃｕｒｉｎｔｈｅｅｎｄ ｍｉｌｌｉｎｇｐｒｏｃｅｓｓｃａｎｏｒｉｇｉｎａｔｅｆｒｏｍａｎｕｍｂｅｒｏｆｓｏｕｒｃｅｓ ,ｓｕｃｈａｓｔｏｏｌｄｅｆｌｅｃｔｉｏｎ ,ｔｏｏｌｗｅａｒ ,ｔｏｏｌｒｕｎ ｏｕｔ,ａｎｄｃｈａｔ ｔｅｒｖｉｂｒａｔｉｏｎ .Ｏｆｔｈｅｓｅ ,ｔｏｏｌｄｅｆｌｅｃｔｉｏｎｉｓｔｈｅｂｉｇｇｅｓｔｐｒｏｂ ｌｅｍｔｈａｔｓｔａｎｄｓｉｎｔｈｅｗａｙｏｆｐｒｅｃｉｓｉｏｎｍａｃｈｉｎｉｎｇ[1,2 ] .…     

压脚压紧力作用下的机器人变形预测和补偿

针对工业机器人在压脚压紧力作用下由于结构变形所引起的压脚沿工件表面滑移的问题,提出压脚约束下的机器人刚度模型,并基于该模型对机器人变形进行预测和补偿,以提高机器人制孔的定位精度. 基于改进的Denavit-Hartenberg方法建立机器人运动学模型;在此基础上,通过研究机器人末端平移变形与压脚压紧力之间的相互耦合关系,建立压脚约束下的机器人刚度模型,通过基于L-M算法的关节刚度辨识实验获得机器人6个关节刚度的具体数值;应用该刚度模型预测一定压脚压紧力作用下不同孔位的机器人末端平移变形,并对理论孔位信息进行离线补偿. 试验结果表明,在采用上述方法补偿机器人滑移变形后,机器人制孔的平均位置误差由原先的0.22 mm降低到0.05 mm,满足机器人自动化制孔定位精度要求.     

双桨无人船转弯半径预报

采用安装有2个螺旋桨的模型遥控船为研究对象,采用滑移网格技术建立实尺度三维混合网格,运用SST模型进行计算流体力学(CFD)仿真. 对该船在静止坐标系下进行自航模拟,通过阻力/推力平衡和单个螺旋桨的偏心位置计算单螺旋桨推进下船的转弯力矩. 建立包含船、桨在内的大区域旋转网格,对该船2种工况下的转弯特性进行数值模拟. 通过插值,可得转弯半径. 对左侧螺旋桨转速为7 560 r/min的实船模型进行转弯实验,测出实船的转弯半径. 数值模拟值与实验测量值之间的相对误差为5.56%,验证了该方法的通用性,为后续双桨水面无人船的精确控制提供数据支持.     

Development of analysis model for geometric error in turning processes

A finite element model was established for analyzing the geometric errors in turning operations and a two-step analyzing process was proposed.In the first analyzing step,the cutting force and the cutting heat for the cutting conditions were obtained using the AdvantEdge.Also,the deformation of a workpiece was estimated in the second step using the ANSYS.The deformation was analyzed for a 150 mm-long workpiece at three different measuring points,such as 10,70 and 130 mm from a reference point,and the amounts...     

采用误差估计补偿的改进型零相位误差跟踪控制

针对伺服系统中零相位误差跟踪控制器(ZPETC)对系统建模误差和参数变化非常敏感的缺点,提出了一种改进型ZPETC设计方法.将信号估计器估计的跟踪误差和系统实时误差作为ZPETC的输入信号,控制器针对系统的跟踪误差进行实时补偿,从而减小零相位误差跟踪控制器受系统参数变化的影响,同时采用低通滤波器(LPF)来消除误差信号中的高频噪声.理论推导与仿真结果表明,该方案在保持伺服系统零相位滞后的同时,减小了系统的跟踪误差,提高了系统的跟踪精度.     

Error compensation for precision machine tools

0　ＩＮＴＲＯＤＵＣＴＩＯＮＦｕｒｔｈｅｒｉｍｐｒｏｖｅｍｅｎｔｏｆｍａｃｈｉｎｉｎｇａｃｃｕｒａｃｙｏｆｍａ ｃｈｉｎｅｔｏｏｌｓｉｓａｌｗａｙｓｔｈｅｏｂｊｅｃｔｏｆｒｅｓｅａｒｃｈｅｒｓｏｆｍａｎｕｆａｃ ｔｕｒｉｎｇ .Ｔｈｅｒｅａｒｅｔｗｏｓｔｒａｔｅｇｉｅｓｔｏｅｎｈａｎｃｅｔｈｅｍａｃｈｉｎｉｎｇａｃｃｕｒａｃｙｏｆｍａｃｈｉｎｅｔｏｏｌｓ :ｅｒｒｏｒａｖｏｉｄａｎｃｅａｎｄｅｒｒｏｒｃｏｍ ｐｅｎｓａｔｉｏｎ .Ｔｈｅｅｒｒｏｒａｖｏｉｄａｎｃｅｓｔｒａｔｅｇｉｅｓａｔｔｅｍｐｔｔｏｍｉ…     

声表面波滤波器衍射迭代补偿的改进算法

高性能声表面滤波器的邻频抑制要求达到60dB以上,此时必须对衍射效应进行补偿．基于δ函数模型,对采用分裂指设计的变迹叉指换能器,通过迭代校正电极孔径大小的方法来改善声表面波滤波器阻带抑制．该算法采用简化的滤波器模型以减少运算复杂度,引入两个误差参数作为迭代补偿结束条件而无需尝试迭代次数．最后给出了一个实际的声表面波滤波器设计实例,用普通PC机不到一分钟便可完成整个设计过程．数值模拟表明,由衍射效应带来的频带恶化基本得到校正．     

轴类零件加工的鼓形误差预报与补偿

根据车削时的力学模型，建立了轴类零件加工中鼓形误差计算的数学模型。采用该模型可预报在给定的加工条件下被加工轴的最大鼓形误差以及数控加工中刀尖的补偿值。分析了所产生误差的原因并提出了减少鼓形误差的措施。最后，给出了计算实例。     

用顺馈校正来提高液压仿形刀架的车削精度

本文应用顺馈校正的方法,从理论上导出了在车床上用液压仿形刀架加工轴类零件减小稳态误差的措施.     

四步相移干涉测量的相位补偿及仿真

在应用相移技术进行相位测量时，相移器的相移误差直接影响相位的测量精度．将快速傅立叶变换技术和四步相移技术相结合，对相位进行补偿，并推出相位误差补偿公式．利用快速傅立斗变换技术求出实际相移量与理论值的相移误差εi，代入相位补偿公式计算相位．通过计算机仿真，采用四步相移算法、四步相移补偿算法得到了各个采样点的相位误差．分析可得，采用四步相移补偿算法比直接采用四步相移算法得到的相位误差有更高的精度，相位误差平均值提高10倍以上．     

某姿态测量系统标定用转台指向误差补偿

为了提高某姿态测量系统的标定精度,研究了其标定设备三轴转台的指向误差补偿方法。分析了影响指向误差的因素;基于多体系统运动学基本原理,阐述了转台系统拓扑结构的低序体阵列;推导了相邻两体间的低序算子;进而建立了关于转台三个回转轴线平均线夹角的指向误差模型;通过仿真结果研究了各误差项对指向误差的影响规律;最后介绍了误差模型参数的测量方法。误差补偿实验验证了方法的有效性和可行性。     

并联六坐标测量机的误差模型和误差补偿

为了探讨并联坐标测量机的机构原始误差和测量过程误差引起测量结果的偏差,在并联六坐标测量机的位置分析基础上,依据矩阵全微分理论,提出了机构原始误差与测头的位置和姿态误差模型。研究了机构参数误差变化对测头的位置和姿态误差的影响,明确了减小测头误差的主要途径是提高测量机零部件的机械加工和装配精确度,严格控制角度误差,给出了在机构参数存在误差的情况下,采用误差直接补偿法修正测头位置和姿态的方法,仿真验证表明,采用软件误差直接补偿法,可以明显提高测量准确度。     

某姿态测量系统标定用转台指向误差补偿

为提高某姿态测量系统的标定精度,对其标定设备三轴转台的指向误差补偿方法进行研究.分析了影响指向误差的因素;基于多体系统运动学基本原理,阐述了转台系统拓扑结构的低序体阵列,并推导出相邻两体间的低序算子;进而建立关于转台三个回转轴线平均线夹角的指向误差模型;通过仿真研究了各误差项对指向误差的影响规律;最后介绍了误差模型参数的测量方法.误差补偿实验验证了方法的有效性和可行性.     

外差激光干涉仪周期非线性误差形成机理与补偿方法

针对纳米级周期非线性误差制约外差激光干涉仪使其不能适应下一代超精密装备制造与重大科学工程提出的亚纳米乃至皮米测量精度需求的问题,分析了外差激光干涉仪中两类周期非线性误差的形成机理,并对周期非线性误差的补偿方法进行了研究.结果表明:第1类周期非线性误差是由于双频激光不能完全分离引起双频激光交叉混叠,进而导致的周期非线性误差,该误差幅度可从数纳米到数十纳米;第2类周期非线性误差是由于测量光束在光学界面产生了具有多阶多普勒频移特征的虚反射光束,进而引入的周期非线性误差,该误差幅度可从数皮米至数纳米.对于第1类周期非线性误差,现有误差补偿方法,如椭圆拟合法等,可将其抑制至0.1 nm量级,特别是空间分离式外差激光干涉仪则从原理上完全消除了这一类误差;而对于第2类误差,通过降低虚反射率和空间滤波可以将第2类误差降低至数十皮米到数百皮米,剩余误差尚不能完全满足皮米测量的精度需求, 亟待发明新的误差抑制或补偿技术.     

Structural scheme and theory behind feedback compensation of new parallel machine tools

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