Investigating the influence of selected factors on results of V-block cylindricity measurements

The article deals with the method of cylindricity measurements using V-blocks. It was assumed, as was in the case of roundness profile measurements before, that the V-block method can be applied to accurate cylindricity measurements of large machine parts directly on a machine tool or a work stand. Results of the statistical verification of the method show that its maximum error equals about 19% in relation to accurate radial method (for the confidence level P = 0.95). The next stage of the research work on the V-block cylindricity measurements was an analysis of potential sources of errors. These sources were divided into two groups: sources independent of the method parameters and sources strictly related to the method parameters. Authors investigated potential sources of errors and developed procedures allowing compensation of influence of most significant ones. The paper provides results of the theoretical and experimental research on an analysis and compensation of main sources of errors of the V-block method of cylindricity measurements.     

Shape optimum design of slider bearings using inverse method

This study aims to develop an algorithm for designing the optimum shape of slider bearing and pressure distribution using an inverse method. The proposed algorithm only needs to obtain the load and moment conditions in order to simultaneously estimate the slider bearing shape and the pressure distribution. The algorithm is developed from the Reynolds integral, and from force and moment balance equations. The least-squares error method, variational method, Gauss–Seidel method and Newton–Raphson method are employed to calculate the optimum shape of slider bearing. Simulation results reveal that as the degree of the shape polynomial function increases, there are corresponding gains in the maximum pressure, load and torque are, and a corresponding decline in the minimum film thickness. On the other hand, the lower the degree of the objective shape polynomial function is, the more accurate the estimated slider bearing shape and pressure distribution are. With increases in degree of polynomial and number of grid points, the errors in the estimated slider bearing shape and pressure distribution can be reduced. The initial guessed values of the coefficients for the estimated slider bearing shape (C_j), the position of the maximum pressure (X_m) and the outlet film thickness (H₀) have notable effects upon the estimated results for the present algorithm. Moreover, the greatest error of initial guessed value is that of C_j, followed by X_m, and then H₀. The estimated pressure distributions are more accurate than the estimated values for film thickness. Consequently, the present algorithm is capable of providing accurate results for slider bearing shape and pressure distribution.     

减少圆柱面上铣槽加工误差的新定位方案

分析了常用的固定V型块独立限位造成定位误差的原因。在探讨了分别采用支承板限位的定位误差以及不同固定形式的定位元件的定位误差的基础上,提出了1种新定位方案。通过计算和比较可知,新方案的定位误差远小于用固定V型块独立限位的定位误差。新定位方案减少了定位误差,即减少了原始误差,有利于提高工件的加工精度。     

Control of an electrostrictive actuator using Newton's method

Electrostrictive actuators are a class of smart transducers with a great potential for many submicron motion applications. A major challenge for the electrostrictive actuators exists in the control of such ultra-precision motions, which are often seriously influenced by the intrinsic behaviors of electrostrictive material like non-linearity, hysteresis and creep. Based on Newton's method, this paper presents a new iterative control algorithm to improve the positioning and tracking performances of a linear multilayer electrostrictive actuator. In this algorithm, the iterative gain is not fixed but variable according to the previous output feedback and the nominal input/output relationship of the electrostrictive actuator. The convergence of this algorithm is theoretically proved quadratic and experimentally verified correct. A comparison of effectiveness of the new algorithm with that of the conventional proportional integral (PI) control and gain-fixed iterative control algorithms is made. The results show that using this new iterative control algorithm both the stability and the speed of submicron motion control have been obviously improved for the tested electrostrictive actuator.     

宽频带记录信号的锋电位检测法

为了考察深部脑刺激的高频电刺激（HFS）期间各种神经元单体的动作电位发放活动,排除电刺激诱发的群峰电位的干扰,设计了一种窗口检测新算法,直接用于检测宽频带记录信号中的锋电位。并且,利用仿真数据和大鼠海马CA1区实验记录数据验证此算法的有效性。结果表明,新算法的锋电位检出率显著大于常规阈值法,而误检率则显著小于阈值法。该算法对于高频刺激期间的仿真数据的锋电位检出率可达95%,误检率则仅为4%;对于7只大鼠的顺向高频刺激实验记录数据的平均锋电位检出率为88 ± 1.4%,而误检率为4.6 ± 1.1%。总之,新窗口法可以正确检测高频刺激期间的锋电位,用于研究各种神经元单体在电刺激期间的不同响应活动,为深入揭示深部脑刺激的神经网络机制提供了有用的新工具。     

Lapping high precision polygonal shafts

Lapping has been used as a finishing method to improve roundness accuracy of cylindrical shafts and holes. However, little has been published on the theoretical analysis of the finishing mechanism for high precision polygonal cross sections. This paper offers a method for finishing polygonal shafts, whose shapes are ellipsoidal, triangular, four-lobed and so on. By this method, the amplitude can be increased for any Fourier component of out-of-roundness. Special types of lapping tools were produced by applying the ‘V-block’ roundness measuring method. Using one of the V-block lapping tools, the magnitude for the four-lobed component was increased form 8.4 μm to 9.9 μm, while the other components were decreased; out-of-roundness improved from 35 μm to 25 μm. By setting the angle between the supporting teeth at an appropriate value, any polygonal shaft can be finished with these laps. This method is also applicable to finishing polygonal holes     

动态隐变量法及其在动态过程监控中的应用

针对动态系统模型难以获取的问题,以提高统计监控性能为目标,对现有的动态隐变量法进行了深入研究.首先指出动态隐变量可包含更多的动态信息,但仍具有自相关,为此提出了采用修正控制图的方法对动态隐变量空间进行检测,而对于自相关不显著的残差空间,指出可按照传统方法或是非参数方法建立控制图;接着将过程知识和经验受控平均运行长度的检验考虑在内,给出了一种时滞变量和时滞长度的确定方法;最后,提出了一种根据残差累积和以及递归特征消除算法(recursive feature elimination,RFE)进行故障变量辨识的方法.通过对双效蒸发过程的应用监控,表明了上述方法的有效性.     

一种二自由度内模控制方法

针对典型的工业过程控制对象，提出了一种二自由度内模控制方法，此方法可以使系统同时具有良好的目标值跟踪特性，干扰抑制特性和鲁棒性，改进了常规内模控制的不足，而且控制算法简单，参数调整方便，理论分析和仿真实验结果表明了它的有效性。     

多视图K-多均值聚类算法

多均值聚类算法假设每个类拥有多个子类,通过求解优化问题的方式来求解每个样本子类的划分和最终类簇的划分.该算法弥补了K-均值算法在非球数据集上的劣势,取得了较好的聚类效果,但是该算法无法被运用到多视图数据集上.本文提出了一种多视图K-多均值聚类算法,保留了K-多均值设置多个子类的设计,引入了视图权重参数,将目标聚类数作为限制条件,通过求解最优问题获得最终的类簇.将本文提出的算法与流行的多视图聚类算法进行对比实验,证明了本文算法的优越性.     

结构体面力重构的边界元逆分析法研究

结构体的边界条件未能充分给出的情况下,用常规边界元法很难作出正确的结构分析。本文利用边界元法与非线性优化技术相结合,根据弹性体内或边界上的位移、应力等附加信息,建立了结构体面力重构的边界元逆分析法的基本模型,算例证明了该理论的有效性。     

遗传算法的数字图像相关搜索法

研究了基于遗传算法(GA)的图像相关搜索方法并进行了实验。实验结果表明:基于GA的搜索方法,u的标准差为0.022 pixel,v的标准差为0.032 pixel。这种方法优于以往的全局搜索法,可以避免初值选取的问题,并且收敛速度快、精度高,适于数字图像相关中非线性、多峰值的全局优化。     

A new minimum zone method for evaluating straightness errors

A new minimum zone method for straightness error analysis is proposed in this article. Based on the criteria for the minimum zone solution and strict rules for data exchange, a simple and rapid algorithm, called the control line rotation scheme, is developed for the straightness analysis of planar lines. Extended works on the error analysis of spatial lines by the least parallelepiped enclosures are also described. Some examples are given in terms of the minimum zone and least-squares. Finally, this easy-to-use method is illustrated by an example that demonstrates that, for a planar line, the minimum zone solution can even be found without the use of a computer.     

A new minimum zone method for evaluating flatness errors

A new minimum zone method for flatnes error analyis is proposed in this article. Based on the criteria for the minimum zone solution and strict rules for data exchange, a simple and rapid algorithm, called the control plane rotation scheme, is developed for the flatness analysis of a flat surface. Experimental work was performed, and some examples are given in terms of the minimum zone and least-squares solutions.     

An upper bound method for analysis of three-dimensional deformation in the flat rolling of bars

A new upper bound method for the analysis of three-dimensional deformation in the flat rolling of bars is proposed. In the conventional upper bound method, stress distribution is not calculated. Hence, a new method of calculating stress distribution is proposed in which the hydrostatic stress in each element and the contact stress on the contact surface between material and roll in each element are calculated. In the conventional upper bound method, the structure of the computer program also depends highly on the kinematically admissible velocity fields assumed. Hence, a new method of analysis in which the structure of the computer program depends minimally on the kinematically admissible velocity fields assumed is proposed. In the analysis of strip rolling, the calculated roll force and roll torque agree with the roll force and roll torque calculated from Sims’ slab method. In the analysis of the flat rolling of bars, the calculated width spread agrees with the width spread obtained by experiments reported in the literature. The effects of a reduction in thickness, roll radius, material width-to-height ratio, front tension, back tension, and front and back tensions on the width spread, forward slip, roll force and roll torque are demonstrated. Hence, the validity of the new upper bound method is confirmed.     

基于神经内分泌的并联机器人智能控制系统

为研究一种高速度、高精度的二自由度冗余驱动并联机器人自适应控制系统,通过建立运动学模型,基于神经内分泌甲状腺激素调节原理,设计了一种带长环、超短环结构的神经内分泌智能控制器,对机器人系统进行控制,并给出了其控制算法。仿真分析结果表明,运动学模型简单有效,使机器人运动过程中各个关节运动稳定、连续且平滑;相对于传统PID控制算法,神经内分泌智能控制算法具有较好的快速响应性、稳定性、鲁棒性、自适应性和抗干扰能力。该方法为机器人的复杂控制提出了一种新思路。     

Fast thickness prediction and blank design in sheet metal forming based on an enhanced inverse analysis method

In sheet metal forming process, inverse analysis codes serve a useful purpose at the early product design stage when an approximate analysis is required to determine if the initial concept part can be made and where the failures and defects will occur. In this paper, a robust energy-based 3D mesh mapping algorithm is used to obtain the initial solution and is followed by a reverse deformation method to improve its accuracy. The novel initial solution scheme can consider the material and the process parameters, and thus lead to fewer Newton–Raphson iterations. The actions of the punch, die, blank holder and the drawbead are fully considered. A fast and reliable boundary condition treatment method is implemented to workpiece without binder and addendum information. Contact treatment between punch and die is an essential issue which greatly affects the convergence of Newton–Raphson iterations. A reliable contact treatment based on topological relations of workpiece is proposed to define the force direction between die and punch. Equivalent drawbead forces are also considered with a simplified model. With the improved aspects, the in-house inverse analysis code InverStamp is developed. Application to a square box and a clover-shaped cup are presented with demonstrations of the validity of the code and the efficiency of the proposed modified approaches.     

图像匹配算法研究

文本讨论了常用图像匹配算法，在介绍了序贯相似性检测法、不变矩法及去均值归一化相关法的基础上，提出了一种以去均值归一化相关法为主的改进匹配算法，该改进算法不但在处理旋转目标的匹配时具有较高的精度，而且通过改进其搜索策略,使改进算法具有了算法速度快、误匹配率低的优点。     

气密封性试验中的泄漏测试方法研究

泄漏测试是材料／结构气密封性试验中经常要遇到的问题。本文在分析传统排水集气方法的基础上,提出了压降 法,详细论述了其测试原理、适用性等,并给出了一个典型的工程应用实例。     

精密并联机器人控制算法及控制系统研究

首次把数字PID算法应用到面向光纤作业的精密并联机器人控制中,介绍了这种高速、高精度小型并联机构控制系统的新控制算法及系统研究情况。另外控制系统采用了DSP新技术,解决了并联机构运动学逆解的实时在线计算问题,使系统运行更加稳定。试验结果表明这种新算法在小型精密并联机构控制系统中,完全可以满足光纤对接等作业的高技术要求,同时也为同类高精度、大行程小型定位系统的控制与设计提供了一种新的实用方法。