关键词: NURBS, 敏感点, 弓高误差, 安全缓冲区

Abstract:

A Non-uniform rational B-spline (NURBS) interpolation algorithm was proposed herein, which was based on the feedrate sensitive point identification. It was crucial for an advanced CNC system compatible with NURBS. The contour errors during rough interpolating calculation were related to the federate at the current point, so it was possible to indentify the feedrate sensitive points according to the chord error during interpolation approximation. The feedrate profile between any two sensitive points should be designed adaptively according to the distance between them, and the security buffer was used. The whole feedrate profile can be generated by feedrate segments combination. A cubic NURBS curve was used to evaluate the interpolation algorithm, and it was simulated under 3 different feedrate commands. Simulation results show that the algorithm is available and can be implemented flexibly according to the different situations of sensitive points. It is also shown that the proposed algorithm guarantees both the contour precision and feedrate smoothness.

Key words: NURBS, sensitive point, chord error, security buffer