TITLE:
Laser Interferometer Based Measurement for Positioning Error Compensation in Cartesian Multi-Axis Systems
AUTHORS:
Y. Echerfaoui, A. El Ouafi, A. Chebak
KEYWORDS:
Multi-Axis Machines, Accuracy Enhancement, Positioning Error, Predictive Modelling, Error Compensation, Laser Interferometer, Artificial Neural Networks
JOURNAL NAME:
Journal of Analytical Sciences, Methods and Instrumentation,
Vol.7 No.3,
September
20,
2017
ABSTRACT: Accuracy is one of the most important key indices to evaluate multi-axis
systems’ (MAS’s) characteristics and performances. The accuracy of MAS’s such
as machine tools, measuring machines and robots is adversely affected by
various error sources, including geometric imperfections, thermal deformations,
load effects, and dynamic disturbances. The increasing demand for higher
dimensional accuracy in various industrial applications has created the need to
develop cost-effective methods for enhancing the overall performance of these
mechanisms. Improving the accuracy of a MAS by upgrading the physical structure
would lead to an exponential increase in manufacturing costs without totally
eliminating geometrical deviations and thermal deformations of MAS components.
Hence, the idea of reducing MAS’s error by a software-based alternative
approach to provide real-time prediction and correction of geometric and
thermally induced errors is considered a strategic step toward achieving the
full potential of the MAS. This paper presents a structured approach designed
to improve the accuracy of Cartesian MAS’s through software error compensation.
Four steps are required to develop and implement this approach: (i) measurement
of error components using a multidimensional laser interferometer system, (ii)
tridimensional volumetric error mapping using rigid body kinematics, (iii)
volumetric error prediction via an artificial neural network model, and finally
(iv) implementation of the on-line error compensation. An illustrative example
using a bridge type coordinate measuring machine is presented.