关键词: 数控系统, 非均匀有理B样条, 插补, 进给速度, 前瞻, 实时

Abstract: To improve accuracy of 5-axis Non-Uniform Rational B Spline(NURBS)interpolation and to cut down mechanical impact on machines during transition, a look-ahead feedrate control method was presented. The computation model of interpolation errors was established by using an approximation method with curvature circle and the relationship between minimum curvature radius and federate, which could meet the requirements of interpolation errors, was also deduced. With the numerical analysis method, parametric value of deceleration point was calculated and then acceleration/deceleration predictive planning was executed on spline interpolation. To the points on the spline curve with smaller curvature radius, feedrate was slowed down to enhance the approximate precision of the interpolated curve in real-time interpolation. The example validated that the proposed method could effectively reduce the interpolation errors and the accelerations in transition. At the same time, the presented method had excellent real-time performance and it could be applied to practical numerical control system.

Key words: numerical control system, non-uniform rational B spline, interpolation, feedrate, look-ahead