Abstract
Variation of the effective moment of inertia due to load disturbance in a CNC feed drive system may increase control error for each axis of motion and thereby degrading total precision including contouring accuracy. Although some investigations have been made on estimation and control of variation of the effective moment of inertia, most of them are for individual axis control: there has been no research that considered the improvement of contouring accuracy in CNC machine tools under load variation. In this paper, a real-time inertia compensation method is proposed including a newly defined contour error model that represents error caused by load disturbance. Position error due to load variation is calculated based on the estimated disturbance torque by a full-order disturbance observer for each drive axis. The position error is then used to establish the new contour error model considering the effect of load variation. The proposed compensation method is realized by adjusting velocity loop gains in the control system using the least square method such that the effect of variation of the effective moment of inertia on the contour error is minimized. The proposed method is evaluated with a 3-axis open CNC testbed.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Koren, Y. and Lo, C. C., “Variable-Gain Cross-Coupling Controller for Contouring,” Annals of the CIRP, Vol. 40, No. 1, pp. 371–374, 1991.
Chiu, G. T.-C. and Tomizuka, M., “Coordinated Position Control of Multi-Axis Mechanical Systems,” ASME Journal of Dynamic Systems, Measurement, and Control, Vol. 120, No. 3, pp. 389–393, 1998.
Jee, S. and Lee, H., “An Integrated Approach to the Analysis and Design of a Three-Axis Cross-Coupling Control System,” Int. J. Precis. Eng. Manuf., Vol. 8. No. 2, pp. 59–63, 2007.
Awaya, I., Kato, Y., Miyake, I., and Ito, M., “New Motion Control with Inertia Identification Function Using Disturbance Observer,” Proceedings of the IECON’92, Vol. 1, pp. 77–81, 1992.
Kim, N.-J., Moon, S.-H., and Hyun, D.-S., “Inertia Identification for the Speed Observer of the Low Speed Control of Induction Machines,” IEEE Transactions on Industry Applications, Vol. 32, No. 6, pp. 1371–1379, 1996.
Koren, Y., “Computer Control of Manufacturing Systems,” McGraw-Hill, New York, 1983.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Jee, S., Lee, J. Real-time inertia compensation for multi-axis CNC machine tools. Int. J. Precis. Eng. Manuf. 13, 1655–1659 (2012). https://doi.org/10.1007/s12541-012-0217-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12541-012-0217-x