Feedrate control for non-uniform rational B-spline motion command generation

This paper presents a real-time feedrate-controlled interpolator (FCI) for accurate feedrate control of computer numerical controlled (CNC) machine tools along non-uniform rational B-spline (NURBS) curves for precision machining. Unlike most of the existing interpolators that are developed based on the Taylor's expansion, the proposed method uses a predictor-corrector algorithm instead. In the predictor stage, an efficient algorithm is used to estimate the servo command of the next sampling time, and in the corrector stage, the errors arising from the prediction can be corrected. This study conducts an extensive mathematical analysis of the FCI, where the criterion for selecting the sampling period, i.e. sampling period bound, is also established. The experimental results are presented to demonstrate the feasibility of the proposed FCI for machining the NURBS curves.