The Real-time Algorithm of NURBS Curve Retriever Interpolation with S-type Acceleration and Deceleration Control

During the high-speed precision machining processes with traditional curve interpolation in single direction, there is no accurate analytical relationship between the curve and the parameter. Furthermore, the feed rate is always restricted by the non-linearly varying curvature and the real-time calculation of the curve length and the prediction of the deceleration point can be difficult. More importantly, the traditional curve interpolation cannot get the rest of speed constraint information and it also can increase the amount of calculation which appears data starvation, then affects the entire real-time system. To solve the above problem, the algorithm of NURBS curve retriever interpolation is proposed. The algorithm applies the forward and reverse asynchronous interpolation method which do not rely on the precise calculation of arc length. The proposed algorithm determines the checkpoint and the relevant information of forward and reverse interpolation in the look ahead interpolation module. In the real-time module, the proposed algorithm determines whether to call the reverse interpolation data or proceed to interpolate by comparing the speed of the checkpoint in order to obtain the optimal interpolation which obey the speed restrictions. At last, the interpolation test not only prove the simplicity, efficiency and adaptability of the algorithm but also the ability to meet the requirements of both high speed and high accuracy of computer numerical control. © 2017 Journal of Mechanical Engineering.