MODELING OF FEEDDRIVE SYSTEMS OF CNC MACHINES

Isias, J.J., and M. Mehrabi

ABSTRACT

 

The feeddrive system is an important component of CNC machines and its performance plays a key role in the accuracy and precision of the entire machining system. This work is mainly focused on modeling of such a system, and the results can be mainly utilized for design, control, and monitoring applications. A 7th order linear model is developed in the state-space format which takes into account the electrical characteristics of the servo system, stiffness, inertia, and damping properties of individual components of the feeddrive system. A detailed parametric study of this model is carried out which reveals the contribution of various components of the system in its transient and steady-state response. The results are used in further simplifying this model to a 4th order systems which is simpler in structure and more appropriate for control applications. A comparison is made between these models and the merits of each individual model are presented. Details of the results are presented and suggestions are made as when to use each of these models.