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Proceedings of CAD'14, 2014, 61-63
Application of an Iterative Learning Control Algorithm to Volumetric Error Compensation for CNC Machines

Ying-Chen Lu, Syh-Shiuh Yeh, National Taipei University of Technology

Abstract. There are two types of error usually considered in CNC machine applications, linear displacement error and volumetric error. Linear displacement error is the positioning error in the axis directions; usually, this error is caused by pitch errors of the leadscrews or linear encoders. Volumetric error is positioning error in a spatial direction that is not necessarily in the axis direction; usually, this error is a given by a vector and its components are linear error, vertical straightness, and horizontal straightness. Because the measured linear displacement error in the diagonal directions of the machine volume is sensitive to the error parallel and perpendicular to the linear motion axes, reduction of linear displacement error cannot completely remove volumetric error. Therefore, to provide precise machining results, both measurement and compensation of volumetric errors must be carefully considered in CNC machines. In recent decades, because of the growth of laser measurement technologies, volumetric error measurement algorithms and devices have been proposed and implemented. There are many advanced CNC machine controllers that provide functions to compensate volumetric errors. However, machines with conventional CNC controllers that are widely utilized in manufacturing mechanical parts usually do not support volumetric error compensation.

Keywords. Iterative learning control, volumetric error, error compensation, CNC machines

DOI: 10.14733/cadconfP.2014.61-63