Effect of servo control frequency on contour errors in a bi-axial CNC machine

In this paper, the relation between servo control frequency and contour error is studied in a bi-axis CNC machine. The objective is to determine the effect of servo control frequency on the contouring accuracy thereby allowing a proper selection of this frequency depending upon the accuracy required. A mathematical analysis is first carried out using a commonly used dynamic model for a servomotor-driven position feedback control system. This was followed by experimental studies in a mini-CNC machine using both the basic linear and circular contours. The results show that the servo control frequency will have effect on contouring accuracies when very high precision are required, in the order of μm.