Dynamic Modeling of CNC Drive Systems: Comparison of Two Models

Accurate positioning and precision of CNC machines are directly affected by performance of their mechanical drive system and control unit (CNC feeddrive system). This is more important in contouring operations where axes motion is synchronized by interpolators and errors are accumulative. This research work is focused on study of dynamics of the feeddrive unit. In this regard, a detailed dynamic model is developed in state-space format that is used to study its response properties. A parametric study of the system is carried out by studying shifts in eigenvalue loci when a parameter is changed. The results are used in further simplifying this model to a reduced order system 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.