Research and Implementation of NURBS Real-Time and Look-Ahead Interpolation Algorithm

In order to meet the numerical control process requirements of high speed and high precision of three dimensional curves, the paper studied on a real-time and look-ahead interpolation algorithm for NURBS (non-uniform rational B-spline) curves. The federate is changed adaptive according to the shape of the curves. A real time look-ahead algorithm is introduced to detect the sharp corners. It is found that the values of the feedrate of the down stream sharp corners have profound effect on the down stream up corners causing ripple effect. By using two look-ahead distances strategy to eliminate all the ripple effect and obtain a continuous velocity and acceleration profile. In this way the impact on the machine is greatly reduced. This is compared with the adaptive NURBS interpolator to show the effectiveness of the proposed method. The experimental results show that the consideration of ripple effect is important in avoiding jerk and thereby increasing the machining accuracy.