Table-Based Volumetric Error Compensation of Large Five-Axis Machine Tools
Table-Based Volumetric Error Compensation of Large Five-Axis Machine Tools
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DOI：
10.1115/1.4034399
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发表时间：
2017-02
影响因子：
4
通讯作者：
J. Creamer;P. Sammons;D. Bristow;R. Landers;P. Freeman;Samuel J. Easley
中科院分区：
文献类型：
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作者：
J. Creamer;P. Sammons;D. Bristow;R. Landers;P. Freeman;Samuel J. Easley
提出了一种大型五轴机床几何误差补偿方法。与小型机床相比，大型机床的轴行程更长，结构更大，这使得它们更容易受到复杂的位置相关几何误差的影响。本文提出的补偿方法使用整个轴空间记录的刀尖测量值来构建机床几何误差的显式模型，从该模型中构建相应的一组补偿表。测量是使用激光跟踪器进行的，可以在轴空间的大多数位置快速收集误差数据。本文考虑了两种位置相关的几何误差模型。第一个模型利用六个自由度的运动误差描述在每个轴。第二个模型的动机是工作台补偿解决方案的结构，并将几何误差描述为对轴命令的小扰动。这两个模型的参数确定从测量数据使用最大似然估计。通过将误差模型投影到由机床控制器中可用的补偿表创建的补偿空间上来生成补偿表。第一种模型比第二种模型更直观地说明了简单的几何误差;然而，它也增加了将误差投影到补偿表上的复杂性。商业五轴机床上的实验结果进行了介绍和分析。尽管在机床误差的描述显着差异，这两种方法产生类似的结果，在机床的可重复性。这种结果的原因进行了讨论。模型和补偿表的分析揭示了显着的复杂，和意想不到的运动学行为的实验机床。所提出的方法的一个特别的优势是同时生成一套完整的补偿表，准确地捕捉复杂的运动误差，独立于它们是否产生预期和意外的来源。
This paper presents a geometric error compensation method for large five-axis machine tools. Compared to smaller machine tools, the longer axis travels and bigger structures of a large machine tool make them more susceptible to complicated, position-dependent geometric errors. The compensation method presented in this paper uses tool tip measurements recorded throughout the axis space to construct an explicit model of a machine tool's geometric errors from which a corresponding set of compensation tables are constructed. The measurements are taken using a laser tracker, permitting rapid error data gathering at most locations in the axis space. Two position-dependent geometric error models are considered in this paper. The first model utilizes a six degree-of-freedom kinematic error description at each axis. The second model is motivated by the structure of table compensation solutions and describes geometric errors as small perturbations to the axis commands. The parameters of both models are identified from the measurement data using a maximum likelihood estimator. Compensation tables are generated by projecting the error model onto the compensation space created by the compensation tables available in the machine tool controller. The first model provides a more intuitive accounting of simple geometric errors than the second; however, it also increases the complexity of projecting the errors onto compensation tables. Experimental results on a commercial five-axis machine tool are presented and analyzed. Despite significant differences in the machine tool error descriptions, both methods produce similar results, within the repeatability of the machine tool. Reasons for this result are discussed. Analysis of the models and compensation tables reveals significant complicated, and unexpected kinematic behavior in the experimental machine tool. A particular strength of the proposed methodology is the simultaneous generation of a complete set of compensation tables that accurately captures complicated kinematic errors independent of whether they arise from expected and unexpected sources.