A Study And Simulation On NURBS Interpolation With Real-time Look-ahead Function

Numerical control technology plays a critical role in modern manufacturing, and interpolation module is the core of the controlling software among the whole numerical control systems. The selection of interpolation algorithm will directly affect the precision and speed of the numerical system. Non-Uniform Rational B-Spline(NURBS) is a widely used parameterization curve, NURBS interpolation technology can enhance processing precision, surface smoothness and production efficiency, thereby improving performance of the numerical control system. Hence, it is of great significance to have a study towards interpolation algorithm.This thesis introduces the NURBS curve in its mathematical module, qualities and related parameters calculation in detail. The author puts forward how to use fast algorithm to compute B-spline functions for speedy evaluation to quicken NURBS curve algorithm. Then, it analyzes the control of the S curve acceleration. By considering the profile error and jerk into consideration, it achieves the NURBS interpolation with real-time look-ahead algorithm. Furthermore, a simulation test is carried out about the NURBS interpolation algorithm. Major fruits about the research are as follows:1. An introduction is made about the NURBS curve mathematical module, qualities and related parameters calculation methods. The author makes a tentative study about how to use B-spline functions for speedy evaluation to quicken NURBS curve algorithm. This approach is more efficient in B-spline interpolation than the calculation based on the de-Boor algorithm.2. This paper puts forward the approach of pre-interpolation S shape acceleration and deceleration control. S shape oriented approach has special advantages in high precision and no rapid change in speed as well as smooth transference. 3. The author devises a NURBS interpolation with real-time look-ahead algorithm. A detailed analysis is made about the computation process. And the computation is divided into sharp corner detection module, speed planning module and real-time interpolation module. This algorithm comprehensively takes into consideration the maximum chord error limited self-adaptive feed speed control, speed control based curvature information and pre-interpolation S shape acceleration and deceleration control based on jerk limit. Pre-interpolation plans the each curve feed speed, then real-time interpolation compute the curve interpolate Points.4. Computer simulation analysis is made towards the given curves by using MATLAB software interpolation algorithm, including the impact on sharp corner made by feeding rate, morphological analysis of the feed rate, data analysis of chord error and processing time, and the curve processing simulation. Thereby testing the accuracy, feasibility andadvantages about the algorithm put forward in this thesis.Therefore, the study of the project has significant theoretical value in promoting numerical control system as well as applicative value in real engineering project.