Feedrate Profile Planning Based on Sensitive Points Identification in NURBS Interpolation

The Non-uniform rational B-spline (NURBS) is widely used in CAD/CAM/CNC. The NURBS interpolation is crucial for an advanced CNC system compatible with NURBS. Classic NURBS interpolation algorithms always do not well consider both the contour precision and feedrate smoothness. This paper proposes a NURBS interpolation algorithm based on the feedrate sensitive points identification. The feedrate sensitive points is found out according to the chord error which is relative to the feedrate passing this point. Furthermore, the feedrate profile is adaptively planned between two adjacent sensitive points according to the distance between them. The feedrate profile of the whole NURBS can be connected with these feedrate sections. A cubic NURBS curve is adopted to evaluate the interpolation algorithm with 3 different feedrate commands. Simulation results show that the proposed interpolation algorithm is available and can be implemented flexibly according to the different situations of sensitive points.