An identifying method with considering coupling relationship of geometric errors parameters of machine tools

Error compensation technology offers a significant means for improving the geometric accuracy of CNC machine tools (MTs) as well as extending their service life. Measurement and identification are important prerequisites for error compensation. In this study, a measurement system, mainly composed of a self-developed micro-angle sensor and an L-shape standard piece, is proposed. Meanwhile, a stepwise identification method, based on an integrated error model, is established. In one measurement, four degrees-of-freedom errors, including two-dimensional displacement and two-dimensional angle of a linear guideway, can be obtained. Furthermore, in accordance with the stepwise identification method, the L-shape standard piece is placed in three different planes, so that the measurement and identification of all 21 geometric errors can be implemented. An experiment is carried out on a coordinate measuring machine (CMM) to verify the system. The residual error of the angle error, translation error and squareness error are 1.5″, 2 μm and 3.37″, respectively, and these are compared to the values detected by a Renishaw laser interferometer.

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Excitation-Contraction Coupling: Relationship of Slow Inward Current to Contraction

Physiology and Pathophysiology of the Heart - Developments in Cardiovascular Medicine ◽

10.1007/978-1-4613-0873-7_10 ◽

1989 ◽

pp. 227-239

Author(s):

Terence F. McDonald

Keyword(s):

Slow Inward Current ◽

Excitation Contraction Coupling ◽

Inward Current ◽

Contraction Coupling ◽

Coupling Relationship ◽

Relationship Of

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Table-Based Volumetric Error Compensation of Large Five-Axis Machine Tools

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4034399 ◽

2016 ◽

Vol 139 (2) ◽

Cited By ~ 11

Author(s):

Jennifer Creamer ◽

Patrick M. Sammons ◽

Douglas A. Bristow ◽

Robert G. Landers ◽

Philip L. Freeman ◽

...

Keyword(s):

Machine Tool ◽

Error Compensation ◽

Machine Tools ◽

Data Gathering ◽

Measurement Data ◽

Geometric Error ◽

Compensation Method ◽

Geometric Errors ◽

Simultaneous Generation ◽

Five Axis

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.

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