The Research On NURBS Adaptive Interpolation Technology

Computer numerical control (CNC) is a key technology in modern machining industry. It integrates the technology of micro-electronics, computer, signal processing, automatic measurement, automatic control and etc. The important norms to value numerical control system performance is the quantity of the interpolation functions. In this thesis, high speed CNC machining oriented NURBS interpolation technology is investigated. Research on this for high speed CNC machining is very important to enhance the performance.This paper discusses NURBS curve and its character and calculating methods of correlation parameter. A new NURBS interpolation algorithm is developed, the 2nd Taylor expansion is employed for next point parametric iteration. Some calculating missions which can be completed in the pretreatment phase. The determination of constrained feed step length based on chord erron controlling and feed acceleration controlling can be adjusted automatically. It can control interpolation error and feed rate in the allowable range at the same time, acquire optimization between interpolation accuracy and feed rate. In the adaptive area, an acceleration/deceleration and jerk limited S curve is used to replan the feedrate. With this interpolation, steady and fast feedrate, confined interpolation error, and a smooth and shock-free machining process is obtained, which enhances the machining efficiency and quality.Real-time NC machining path emulation is executed with MATLAB based on the new interpolation arithmetic and new algorithm of S shape Acceleration-Deceleration. And the arithmetic has been proved to be correct, effective and having real-time character. This study makes preparations for empoldering new generations of the CAD/CAM/CNC.