Design And Implementation Of NURBS Interpolation With FPGA Device

CNC technology is a very critical part of modern manufacturing technology, and theinterpolation module is the core of the entire CNC system control software, so the achievementof the interpolation module has a direct impact on the speed of the CNC system. As it has manyadvantages in complex geometric modeling, NURBS method is widely used in CAD/CAM.NURBS interpolation technology not only can improve the machining accuracy, surfacesmoothness and production efficiency, but also can greatly improve the trajectory function ofCNC system.For high-speed and high-precision CNC system, NURBS interpolation technology isparticularly important. Due to the complexity of computation, the motion controller based on anordinary PC or ARM plus DSP architecture is difficult to complete the NURBS interpolation in asmaller sampling period(for example,1ms). Tsai et al found that calculating a NURBS curveinterpolation and servo control costed4ms, while NURBS interpolation calculation needed3.8ms, accounting for95%of computing time. Obviously, for high-speed and high-precisionmotion controller, NURBS takes up too much time. With the development of programmablelogic technology, field programmable logic devices (FPGA) appeared, and they have low prices,excellent parallel computing power and flexible programming capabilities and are suitable forengineering applications, therefore, using FPGA to complete NURBS curve interpolation has avery practical significance.This paper analyzes some traditional NURBS curve interpolation algorithm, and makes adeep research on Cox-de Boor algorithm, which doesn’t compute base function, and completesthe algorithm using FPGA. With the increase of dimension, this realization way also has verygood real-time performance. The simulation and experimental results prove that the NURBScurve interpolation based on FPGA has good computing power. The main research work andachievements of this paper include:Firstly, introduce the mathematics model, the quality and related parameters calculationmethod of the NURBS curve. And introduce how to solve NURBS curve algorithm with theCox-de Boor in detail.Secondly, design a NURBS curve interpolation based on FPGA after introduced Quartusdevelopment tool, high-speed hardware description language Verilog HDL. Systematicallydescribe the system functions, logic function and the core sub-module functional of the system indetail.Finally, compelte a NURBS curve interpolation based on FPGA, using the programminglanguage Verilog. Simulate sevral given NURBS curves and compare with NURBS curveinterpolation based on the PC, the results demonstrate the real-time and superiority of thesystem.Therefore, the study of this project has significant theoretical value in promoting numericalcontrol system as well as applicative value in real engineering project.