三维空间中圆度误差的评定研究

为解决三维空间中圆度误差的精确评定问题,针对三坐标测量机检测圆度误差时因存在测量误差而使各实际测点不是精确地位于同一理想截平面上的特点,根据计算几何学和误差理论,提出了基于空间测点集算术平均中心点的最小二乘平面拟合方法,推导了其数学模型;并对国家标准中圆度误差评定的最小外接圆法、最大内接圆法和最小区域圆法进行了三维扩展;还对前两种方法作了改进,建立了此3种方法的数学模型和算法流程。最后的数字实验表明:以上3种算法是有效的。     

基于改进果蝇优化的机械圆度误差评定研究

针对机械零件圆度误差的最小区域圆法评定问题,提出一种基于改进果蝇优化算法的评定圆度误差新方法。首先根据最小区域圆法圆度误差数学描述的优化模型设计了果蝇种群个体的编码方式以及新型味道浓度判定函数;其次在保持基本果蝇优化算法典型流程的基础上,引入增强搜索和交互学习机制来增强算法的学习效率以及保持种群的多样性;最后采用3个典型的圆度误差评定问题来验证算法性能。实例分析计算表明该方法是可行有效的,其结果具有较高精度且优于传统的评定方法,适用于求解圆度误差的评定优化问题。     

基于遗传算法的圆度误差评估

将遗传算法应用于圆度误差的评定.首先简介了误差评定背景和遗传算法及其特点.然后根据尺寸和公差的数学定义^[1]给出满足最小区域条件的圆度公差评定的数学模型和适应度函数.接着,以最小二乘解作为初始值,对圆度误差的遗传优化过程进行了详细的论述.最后用实例对算法进行验证.优化过程和实验结果显示了遗传算法在解决形状公差的评定这类非线性问题的优越性,通过并行搜索能最大限度地保证解的全局最优,计算精度高、效率高,且易于理解和实现.     

基于混合搜索算法的圆度误差评定

加工中因各种因素导致回转类零件产生几何误差,而圆度误差作为重要的几何误差直接影响机器配合精度与性能,因此,准确评定零件的圆度误差显得格外重要。本文提出一种精确评估圆度误差的混合方法,由区域搜索算法和三角形搜索算法两部分组成。区域搜索算法用于区域的全局搜索,找到准圆心,再运用三角形搜索算法,根据限制条件进行精细搜索,找到最小包容区域圆心完成圆度误差评定。本方法无需满足小误差和小偏差假设,对采样点数与采样策略没有要求。通过仿真验证了本文方法的可行性,并对实例验证与试验验证进行评定与比较。结果表明,本方法比PSO算法和文献中的算法评定精度更高,不存在模型误差与原理误差,对采样点分布与数量没有限制,可以准确找到最小包容区域圆心。     

圆度误差评定方法的研究

圆度误差评定是否准确,将直接影响到机械产品的性能和寿命.介绍了4个简单而有效的算法来评定圆度误差,即最小外接圆、最大内接圆、最小区域法和最小二乘圆法.利用MATLAB对上述算法进行了验证,说明文中算法有效.     

基于几何优化的圆度误差评定算法

针对圆度误差的特点,提出一种基于几何优化的圆度误差评定算法。建立直角坐标采样、可同时实现圆度误差的最小区域法、最小外接圆法和最大内接圆法评定的评定模型。详细阐述利用几何优化算法求解圆度误差的过程和步骤,给出数学计算公式及计算机程序流程图。该算法不要求等间隔测量,不采用最优化及线性化方法,也无需满足小误差和小偏差假设,只需重复调用点与点之间的距离公式;其原理是以初始参考点为基准,布置一定边长的正六边形,依次以各顶点为理想圆心计算所有测点的半径值,通过比较、判断及重复设置六边形来获得相应评定方法(最小区域圆法、最小外接圆法和最大内接圆法)的圆度误差值。试验结果表明,该算法可以有效、正确地评定圆度误差。     

基于fminimax优化函数的圆度误差评定

依据圆度误差标注代号和附加符号的含义,基于最小外接法、最大内切法和最小区域法分别建立了参考圆的圆心坐标优化目标函数和圆度误差评定模型,采用MATLAB软件编写了参考圆的圆心坐标优化目标函数子程序和圆度误差评定子程序,给出了圆度误差评定中fminimax优化函数调用方法。用Talyrond 585LT圆柱度测量仪对三个试样的圆周轮廓进行了提取,基于最小二乘法、最小外接法、最大内切法和最小区域法对提取的圆周轮廓分别进行了圆度误差评定。研究了优化搜索范围对圆度误差评定结果的影响,并将fminimax优化函数圆度误差评定的优化符合度与其他优化方法圆度误差评定的优化符合度进行了比较。fminimax优化函数的应用结果表明,评定结果精度高于或等于其他优化方法评定结果的精度,可满足圆度误差评定的需要。     

AutoCAD在圆度误差评定中的应用研究

在圆度误差测量中,圆度误差的数据处理和评定一般都是采用绘制简图及用同心模板逼近的方法完成,但这种方法处理效率及准确度偏低。应用AutoCAD软件的绘图和标注功能对圆度误差进行评定的方法,能够很好的弥补传统方法的不足。     

Circularity error evaluation: Theory and algorithm

Many procedures for the evaluation of circularity error based on different criteria have been developed. The procedures that are based on the minimum radial separation criterion are either too complex or lack an algorithmic approach to find optimal solution. This paper presents an optimization-based technique to find the value of circularity error based on the minimum radial separation criterion. The problem is formulated as a nonlinear optimization problem. Based on the developed necessary and sufficient conditions a generalized nonlinear optimization procedure is presented. The performance of the developed procedure is analyzed for different size problems generated using a simulation program. Results indicate that the procedure is accurate and very efficient in solving large size real life problems.     

Fast genetic algorithm for roundness evaluation by the minimum zone tolerance (MZT) method

According to ISO 1101, “A geometrical tolerance applied to a feature defines the tolerance zone within which that feature shall be contained”.The main goal of the minimum zone tolerance (MZT) method is to achieve the best estimation of the roundness error, but it is computationally intensive. This paper describes the application of a genetic algorithm (GA) to minimize the computation time in the evaluation of CMM roundness errors of a large cloud of sampled points.Computational experiments have shown that by selecting the optimal GA parameters, namely a combination of the five genetic parameters related to population size, crossover, mutation, stop condition, and search space, the computation time can be reduced by up to one order of magnitude, allowing real-time operation.Optimization has been tested using seven CMM samples, obtained from different machining features. The performance of the optimized algorithm has been validated using four benchmark samples from the literature and with certified samples.     

Roundness error evaluation algorithm based on polar coordinate transform

A new method for roundness error evaluation using polar coordinate system, named as polar coordinate transform algorithm (PCTA), was presented in this paper. The algorithm first allocates a circular region around the least square circle center following certain rules, then calculates the polar radius for all measured points by translating polar coordinate system to each point in the region in turn, and finally obtains minimum circumscribed center point, maximum inscribed center point and minimum zone center point from comparing each polar radius relative to each polar coordinate system. With accurate center point, the algorithm could give more accurate roundness evaluation. In the paper, the process of PCTA was described in detail including the algorithm formula and flowchart. Theoretical calculation and testing results show that PCTA can evaluate roundness error effectually and accurately.     

Conicity error evaluation using sequential quadratic programming algorithm

Form error evaluation plays an important role in processing quality evaluation. Conicity error is evaluated as a typical example in this paper based on sequential quadratic programming (SQP) algorithm. The evaluation is carried out in three stages. Signed distance function from the measured points to conical surface is defined and the cone is located roughly by the method of traditional least-squares (LS) firstly; the fitted cone and the measured point coordinates are transformed to simplify the optimal mathematical model of conicity error evaluation secondly; and then optimization problem on conicity error evaluation satisfying the minimum zone criterion is solved by means of SQP algorithm and kinematic geometry, where approximate linear differential movement model of signed distance function is deduced in order to reduce the computational complexity. Experimental results show that the conicity error evaluation algorithm is more accurate, and has good robustness and high efficiency. The obtained conicity error is effective.     

改进型遗传算法在机械优化设计中的应用研究

针对标准遗传算法局部搜索能力弱的特点,将其与随机方向法结合,提高其局部搜索能力。结合工程问题进行优化计算,结果表明,此算法优于标准遗传算法。     

基于遗传算法的机器零件圆柱度误差评定方法研究

为解决机器零件圆柱度误差在线评定过程复杂和精度较低的问题,将遗传算法应用于圆柱度误差在线评定方法的研究中。根据测量装置的工作原理,建立了圆柱度误差评定的数学模型,并对其进行了简化;采用实数编码和引入迁移算子的遗传算法对最小区域圆柱度误差进行了评定,通过设计圆柱度误差在线检测装置,利用Matlab和VC混合编程的方式,完成了圆柱度误差评定系统的构建,最后采用实验数据对系统性能进行了测试。研究结果表明,所构建的误差评定系统能够简化误差评定过程,并可满足机器零件精度检验的要求。     

圆度误差的网格搜索算法

本文提出了一种新的圆度误差评定方法—网格搜索算法,详细论述了该算法求解圆度误差的原理和步骤。该算法不采用最优化及线性化方法,其原理是在最小二乘圆心周围按一定规则布置一系列的网格点,依次以各网格点为理想圆心计算所有测点的半径值,按照圆度误差的定义即可获得相应评定方法(最小区域圆法、最小外接圆法和最大内接圆法)的圆度误差值。试验及仿真结果表明,网格搜索算法可以有效、正确地评定圆度误差。     

基于改进的遗传算法的装配序列规划

针对装配序列规划问题的特点,设计了具有针对性的杂交算子和变异算子.并应用Boltzman变比技术对遗传算法进行了改进,提出了一种基于改进的遗传算法的装配序列规划的方法.通过使用精英选择技术,保证最优种群能进入到下一代中.提出了一种应用简化关联图生成遗传算法初始种群染色体的方法,应用该方法并结合人工输入的方法,可以保证初始种群染色体的质量.实际应用证明,该方法比传统方法更加有效.     

基于改进遗传算法的时间最优轨迹规划

提出一种工业机器人时间最优轨迹规划方法.将机器人关节空间的轨迹视为拟合关键点的三次样条曲线,以最优时间为目标建立最优时间轨迹规划的数学模型,同时考虑关节轨迹速度、加速度和加加速度的约束,结合目标函数值和约束条件提出一种用于进化算法的排序方法,以改进遗传算法为例优化关节空间的三次样条轨迹.应用谢菲尔德(Sheffield...     

电磁轴承转子表面圆度误差对系统的影响

通过对转子表面圆度误差的机理分析,建立了圆度误差的数学模型,并实验验证了数学模型的正确性。分析讨论了圆度误差对采用PID控制策略的电磁轴承系统的控制精度的影响。研究结果表明:圆度误差会使转子作周期振动,当圆度误差信号的频率等于系统固有频率时,振动幅值较大,在这个频率后随频率的增加振动幅值减小。