油管壁厚测量数据的一致性加权融合估计算法

在随机拔动环境中采用漏磁场法在线测量油管壁厚时，每个磁性传感器只能得到环境的部分信息。为了对各传感器的局部测量值进行稳健融合估计，提出了油管壁厚测量数据的一致性加权融合估计算法。利用改进的数据探测技术中的分布图方法对各个传感器的一致性进行检验，并采用简单加权平均法求得一致性传感器测量数据的稳健融合估计值。融合实例表明，该算法能有效地提高系统测量的稳健性，且具有精度高、运算简单等特点。该算法适用于多传感器测量数据的实时高精度融合估计。     

基于最近统计距离的多传感器一致性数据融合

为了剔除多传感器测量数据中的疏失误差,一致性数据融合方法得到广泛研究。在已有方法的基础上,定义了一种新的用于衡量传感器测量数据之间支持程度的统计距离,并在此统计距离的基础上,提出了一种基于最近统计距离的多传感器一致性数据融合新方法。数值仿真实验的结果表明,和已有方法相比,新定义的统计距离更能合理地反映传感器测量数据之间的支持程度,同时,整个融合过程的计算复杂度和计算量明显降低。     

多传感器数据融合新算法及在诊断学中的应用

着眼于复杂装备系统诊断实践中多传感器数据融合需求,提出了一种基于模糊贴近度的数据融合新算法,通过计算各个传感器测量值与估计值之间的模糊格贴近度,确定它们在测量中的权重,从而实现多传感器诊断参数数据融合.结合该算法原理,还设计了它的诊断数据融合应用软件.应用实例表明该算法体现了稳定性强、可靠性高的传感器在数据融合中的"优越性",运算过程简洁、快速,运算方法可行、有效,便于发动机诊断中实现时环境测量与数据处理.     

多传感器数据融合新算法及在诊断学中的应用

着眼于复杂装备系统诊断实践中多传感器数据融合需求,提出了一种基于模糊贴近度的数据融合新算法,通过计算各个传感器测量值与估计值之间的模糊格贴近度,确定它们在测量中的权重,从而实现多传感器诊断参数数据融合.结合该算法原理,还设计了它的诊断数据融合应用软件.应用实例表明:该算法体现了稳定性强、可靠性高的传感器在数据融合中的"优越性",运算过程简洁、快速,运算方法可行、有效,便于发动机诊断中实现时环境测量与数据处理.     

相关系数平稳序列数据融合方法

相关系数平稳序列是从非平稳序列中分离出来的一类工程实际中常见且便于研究的随机序列，传统的平稳序列只是它的一个特例。文中建立了多传感器对同一相关系数平稳序列进行测量时的数据融合方法，其中包括相关系数平稳序列的集中式融合和分布式融合两种方法。大量模拟实验表明，通过多传感器的数据融合，相关系数平稳序列的滤波精度比任何单一传感器的滤波精度都有较大提高。     

多传感器数据融合技术在动态称重系统中的应用

利用多传感器数据融合技术,通过对超声波传感器、测速传感器、电容传感器以及称重传感器测得的物料质量数据进行数据融合,大大提高了称重系统的测量精度,得到受环境干扰因素更小、精度更高的有关物料的测量数据。仿真结果表明,该方法在数据处理的精确性和稳定性方面都得到改善,可以有效地减小噪声、振动、电磁干扰等环境因素对动态称重系统测量的影响。     

基于神经元的多传感器数据级融合研究

在不知道先验知识的条件下,从含有观测噪声的多传感器测量数据中估计出方均误差最小的数据融合值,并作为神经元融合系统训练样本,因而解决了多传感器测量系统数据级融合的标定问题。研究结果表明,融合数据在精度、容错性以及动态响应方面均优于单传感器测量。     

复杂曲面形貌无影视觉测量研究

结构光测距技术的主要缺点是无法获取摄像机看不到或光源照不到的点的数据。为此，采用冗余多传感器构成无影视觉坐标测量系统。传感器输出各自测得的目标参数和状态参数到数据融合中心，特殊设计的可变模板抽提出各路信号的特征参数。利用特征参数阈值进行数据特征融合后，进行加权融合计算，使融合后的最终测量结果达到最优。实验证明，无影视觉系统明显优于单目测量系统，对复杂形貌曲面测量有重要意义。     

基于神经网络的大直径测量多传感器数据融合

多传感器数据融合技术可以避免单一传感器的局限性,充分利用不同时间和空间的测量数据信息,大大提高测量系统的性能和效率。本文将BP神经网络应用于大直径测量系统的特征层数据融合,得到准确的测量结果。     

基于相关函数的多振动信号数据融合方法

为提高振动数据测量的精度,提出了一种根据相关函数确定权值进行数据融合的方法.该方法在不知道传感器测量数据任何先验知识的情况下,可依据各传感器所测数据相关程度的变化,及时调整参与融合的各传感器权值.该方法简单易行,动态适应性好,抗干扰能力强.通过仿真试验表明,该方法的融合结果在精度、容错性方面均优于传统的平均值加权法,最后在旋转机械故障诊断中进行了实际应用,验证了该方法的可行性.     

Error Compensation of Thin Plate-shape Part with Prebending Method in Face Milling

Low weight and good toughness thin plate parts are widely used in modern industry, but its flexibility seriously impacts the machinability. Plenty of studies focus on the influence of machine tool and cutting tool on the machining errors. However, few researches focus on compensating machining errors through the fixture. In order to improve the machining accuracy of thin plate-shape part in face milling, this paper presents a novel method for compensating the surface errors by prebending the workpiece during the milling process. First, a machining error prediction model using finite element method is formulated, which simplifies the contacts between the workpiece and fixture with spring constraints. Milling forces calculated by the micro-unit cutting force model are loaded on the error prediction model to predict the machining error. The error prediction results are substituted into the given formulas to obtain the prebending clamping forces and clamping positions. Consequently, the workpiece is prebent in terms of the calculated clamping forces and positions during the face milling operation to reduce the machining error. Finally, simulation and experimental tests are carried out to validate the correctness and efficiency of the proposed error compensation method. The experimental measured flatness results show that the flatness improves by approximately 30 percent through this error compensation method. The proposed method not only predicts the machining errors in face milling thin plate-shape parts but also reduces the machining errors by taking full advantage of the workpiece prebending caused by fixture, meanwhile, it provides a novel idea and theoretical basis for reducing milling errors and improving the milling accuracy.     

曲柄滑块机构的运动误差补偿

在实际的机械系统中,由于构件的加工、装配误差和磨损,机构系统中一定会存在误差。误差的存在会影响机械系统的稳定可靠性和运动精度,使得实际机构和理想机构之间存在运动误差。现代机械工业正向着高精度、高速度、高效率的方向发展,如何减小机械系统中的误差是一个关键问题。本文应用曲柄滑块机构为例,提出一种增加一个自由度的方法,把曲柄滑块机构改装成五杆机构,通过控制新增的自由度来减小系统误差的方法。运用开环运动补偿控制和PID闭环控制方法对五杆机构进行控制,从而提高系统的可靠性和运动精度。实验结果表明:所提出的方法能够有效的减小机构系统中的误差,提高了曲柄滑块机构的运动精度。     

Prediction and compensation of machining geometric errors of five-axis machining centers with kinematic errors

Kinematic errors due to geometric inaccuracies in five-axis machining centers cause deviations in tool positions and orientation from commanded values, which consequently affect geometric accuracy of the machined surface. As is well known in the machine tool industry, machining of a cone frustum as specified in NAS979 standard is a widely accepted final performance test for five-axis machining centers. A critical issue with this machining test is, however, that the influence of the machine's error sources on the geometric accuracy of the machined cone frustum is not fully understood by machine tool builders and thus it is difficult to find causes of machining errors. To address this issue, this paper presents a simulator of machining geometric errors in five-axis machining by considering the effect of kinematic errors on the three-dimensional interference of the tool and the workpiece. Kinematic errors of a five-axis machining center with tilting rotary table type are first identified by a DBB method. Using an error model of the machining center with identified kinematic errors and considering location and geometry of the workpiece, machining geometric error with respect to the nominal geometry of the workpiece is predicted and evaluated. In an aim to improve geometric accuracy of the machined surface, an error compensation for tool position and orientation is also presented. Finally, as an example, the machining of a cone frustum by using a straight end mill, as described in the standard NAS979, is considered in case studies to experimentally verify the prediction and the compensation of machining geometric errors in five-axis machining.     

Kinematic errors identification of three-axis machine tools based on machined work pieces

Evaluating machine tool performance under machining conditions is generally used as the final test in machine tool industry. The seventh part of ISO-10791 describes a machining test using the accuracy of a finished work piece to determine the accuracy of three-axis machine tools. However the kinematic errors cannot be distinguished from each other by means of these test pieces. In this paper a new method to identify the kinematic errors of three-axis machine tool is proposed. A set of test pieces are designed where the kinematic errors of a machine tool can be measured separately along X, Y and Z directions. A volumetric error model is also presented based on the measured errors. This method is initially evaluated in virtual environment and then with some test pieces designed for this purpose. The results are compared with the laser interferometry measurements. It is shown that the measured positioning and straightness errors are consistent with the laser interferometry results. Angular errors measured by the test pieces are also complied with the laser interferometry results as long as the angular error magnitudes are large enough.     

法兰密封专家系统开发研究

通过Delphi5.0开发平台，利用可视化和面向对象技术以及数据和功能的模块化开发思想，依据国家标准及相应的行业标准，基于专家知识和经验开发尘兰密封专家系统，该系统可以实现尘兰密封元件选用及管理的自动化和智能化，能够降低密封设计和管理的工作量，避免人为错误，同时，本系统采用动态构件和DLL（动态连接库）技术，减小推理机推理过程的复杂性，降低其冗余度，可以增强程序的可移植性和开放性，提高开发效率。     

基于Hilbert变换的全封闭压缩机转速测量

近年来,制冷工业对制冷压缩机转速的测量精度要求日益增加,传统的直接测量法对压缩机本身都具有破坏性,而基于外壳振动的间接测量方法,对测试条件要求高,且测量误差较大。为提高测量精度,满足工业需求,提出一种基于Hilbert变换的信号提取方法,针对压缩机的活塞运动规律和感生电动势变化间接反映的压缩机转动特性进行信号提取。该方法精确度高、抗干扰强。与可视压缩机直接测量对比,其转速误差小于2r/min。     

Wall thickness error prediction and compensation in end milling of thin-plate parts

End milling has been widely adopted to machine the thin-plate parts that play increasingly important role in the aerospace industry, due to the advantages of high machining accuracy and fine machined surface quality. In this paper, a systematic method is proposed to predict and compensate the wall thickness errors in end milling of thin-plate parts. The errors are caused by the static deflections induced by the varying cutting force imposed on the weakly rigid part. To improve the efficiency of computing the part deformation, a novel FE model is firstly developed by combing the methods of substructure analysis, special mesh generation and structural static stiffness modification. Then, the time- and position-dependent deformations of the part are calculated based on the proposed FE model to predict the wall thickness errors left on the finished part. It reveals for the first time that the surface topography of the finished thin-plate part is formed by the repeated cutting with the bottom edge of the cutter (BEC) in end milling. Owing to the coupling between the axial cutting depth (ACD) and the force-induced deflection, the modified ACDs for compensation of the static wall thickness errors are finally determined by an iterative adjustment method. The proposed method is verified by three-axis end milling experiments. The experiment results show that the predicted wall thickness errors match well with the really measured ones, and the errors are reduced by 77.18% with the help of the proposed compensation method. Moreover, the proposed FE model reduces the computational time elapsed for error prediction by 67.44% as compared with the benchmark FE model.     

轮胎模具三轴数控加工方法研究

轮胎花纹是影响轮胎性能和使用寿命的主要因素,轮胎模具加工中花纹块加工是主要的技术难题,制造最困难的也是胎面的花纹.本文针对运用三轴数控技术加工轮胎模具生产中轮胎模具加工存在很大误差的问题,提出并验证了一种用三轴加工轮胎模具的花纹制造的新方法,为轮胎花纹分块加工,减少误差提供理论依据.在实际生产中效益较好.     

Fractional-order PID design: Towards transition from state-of-art to state-of-use

This paper presents a new tuning method for fractional-order (FO)PID controllers to simplify current tuning and make FOPID controllers more convenient for industry, i.e. facilitate transition from state-of-art to state-of-use. The number of tuning parameters is reduced from five to three based on popular specification settings for PID controllers without the need for reduced process models which introduce modeling errors. A test batch of 133 simulated processes and two real-life processes are used to test the presented method. A comparative study between the new method and the established CRONE controller, quantifies the performance. The conclusion states that the new method gives fractional controllers with similar performances as the current methods but with a significantly decreased tuning complexity making FOPID controllers more acceptable to industry.     

动态测量数控机床的几何误差

数控机床的检测与修正是机床行业中的一个关键组成部分,每个国家都有相应的测量数控机床几何位置精度,特别是静态几何精度的标准。由于工件是在动态的过程中进行加工,数控机床的静态精度并不能完全代表其几何位置精度,对于某些精密加工和高速加工场合,必须对数控机床进行动态测量补偿,本文介绍了一种动态测量数控机床位置精度的系统,并给出了一些动态误差的实验结果。