基于DSP的NURBS直接插补技术研究
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
NURBS方法以其在复杂几何造型方面的诸多优势,在CAD/CAM和计算机图形学领域得到越来越广泛的应用。但是,传统的数控机床一般只有直线和圆弧插补功能,必须借助CAM系统将其离散成大量微小直线段再传到CNC系统中加工,难以满足当今高速高精加工的要求。因此,研究NURBS直接插补技术对于开发高速高精CNC系统具有十分重要的意义。
     本文结合浙江省重大机电装备专项项目(2006C11067)的科研任务,在深入分析NURBS相关理论知识和数控运动控制技术基础上,提出了新的NURBS直接插补算法。
     NURBS直接插补主要分两个步骤完成:轨迹空间到参数空间的映射和参数空间到轨迹空间的映射,综合运用解非线性方程法和de Boor算法实现NURBS直接插补,简化了插补运算,提高了插补效率。同时,本文提出的前瞻自适应算法,使进给速度能根据曲线形状自动进行调整,同时回溯和重插补策略可以保证加工过程中机床运动学参数控制在允许范围内,防止出现大的冲击和振动,提高表面加工质量。为了将危险点的对速度曲线的影响纳入到前期速度规划中,第四章在分段插补思想基础上提出了新的NURBS插补策略。最后,利用NURBS的对称性进行反向插补,实现了对减速点位置的准确预测。
     本文算法最终移植到基于DSP TMS320F2812的运动控制卡上,分别从硬件和软件两个方面详细介绍了算法的移植过程。硬件方面着重介绍了DSP上专门用于电机控制的事件管理器的配置情况,包括引脚、定时器、周期寄存器、比较寄存器的配置等;软件方面详细介绍了旋转缓冲区技术、IQmath库引入等。
     最后,对NURBS直接插补算法进行仿真分析和实验研究。利用Xk713数控铣床搭建实验平台,并设计了一条既有尖角和又有高曲率点的三次NURBS曲线进行加工实例加工,通过与传统算法比较,借助图形图表等手段分析插补算法在插补效率、精度、运动学参数等方面的性能表现,验证算法的可行性和可靠性。
NURBS is more and more widely applied in the field of CAD/CAM and computer graphics because of its unique advantages in modeling complex parts. However, traditional CNC machine tools only have the direct interpolation function of line and arc, so it's necessary to turn the curves into tiny segments with CAM and then transfer the data to CNC systems. It can't meet the demand of high efficiency and high precision. So the direct interpolation of NURBS is of great significance to the development of CNC machine tools of high efficiency and precision.
     This paper proposed a new direct interpolation algorithm of NURBS with the support of the Science and Technology Project of Zhejiang Province (NO. 2006C11067).
     There are two steps to realize the direct interpolation of NURBS, first mapping the path into parameters and then mapping the parameters into path. Nonlinear equation method and de Boor algorithm are used to simplify the process and improve the efficiency. In addition, the feed rate optimization is another important task for the direct interpolation of NURBS. Feed rate Adaptation Control Algorithm modifies the feed rate according to the curvature of the curve, meanwhile the look-ahead algorithm with back tracking and re-interpolation strategy keeps the dynamics parameters under control to prevent shocks and vibrations. To take the effect of dangerous points into consider during the planning of feed rate, segment interpolation scheme is proposed in Chapter Four. The symmetry of NURBS is used to predict position of the decelerating point precisely.
     The algorithm is transplanted to the motion control card based on TMS320F2812. In term of hardware, the settings of EV are explained in details, including I/O, GP Timer, Period Register, and so forth. Meanwhile, the tech of circular buffer and IQ math library are introduced in term of software.
     Finally, analysis of simulations and experiments are conducted to verify the viability and reliability of the algorithm. Xk713 CNC miller and an specific designed NURBS curve are applied in the experiments. The performance of the algorithm in efficiency, precision and axis dynamics is compared with the traditional methods.
引文
[1]王爱玲.机床数控技术[M].北京:高等教育出版社,2006:10-18.
    [2]陈蔚芳,王宏涛.机床数控技术及应用[M].北京:科学出版社,2005:146-148.
    [3]朱新雄.自由曲线曲面造型技术[M].北京:科学出版社,2000.
    [4]施法中.计算机辅助几何设计与非均匀有理B样条[M].北京:高等教育出版社,2001.
    [5]赵巍.数控系统的插补算法及加减速控制研究[D].天津:天津大学,2004.12:54-63.
    [6]黄翔,曾荣等.NURBS插补技术在高速加工中的应用研究[J].南京航空航天大学学报,2002,34(1):82-85.
    [7]Shipitalni M,Koren Y,Lo CC.Real-time curve interpolation[J].Computer-Aided Design,1994,26(11):832-838.
    [8]Yang DCH,Kong T.Parametric interpolator versus linear interpolator for precision CNC machining[J].Computer-Aided Design,1994,26(3):225-234.
    [9]Forouki RT,Tsai YF.Exact Taylor series coefficients for variable-feed rate CNC curve interpolators[J].Computer-Aided Design,2001,33:155-165.
    [10]M.-Y.Cheng,M.-C.Tsai,J.-C.Kuo.Real-time NURBS command generators for CNC servo controllers[J].International Journal of Machine Tools & Manufacture,2002,42:801-813.
    [11]W.T.Lei,M.P.Sung,L.Y.Lin,J.J.Huang.Fast real-time NURBS path interpolation for CNC machine tools[J].International Journal of Machine Tools and Manufacture,2007.8,10(47):1530-1541.
    [12]Marchenkl Tikhon,Tae Jo Ko,Seung Hyun Lee,Hee Sool Kim.NURBS interpolator for constant material removal rate in open NC machine tools[J].International Journal of Machine Tools & Manufacture,2004,44:237-245.
    [13]C.-W.Cheng,M.-C.Tsai.Real-time variable feed rate NURBS curve interpolator for CNC machining[J].The International Journal of Advanced Manufacturing Technology,2004,(23):865-873.
    [14]宋本基.数控技术[M].哈尔滨:哈尔滨工程大学出版社,1999.
    [15]陈绍平.三次NURBS曲线的插值与应用[J].机械科学与技术,2001.9,20(5):692-693.
    [16]Zhang Deli,Zhou Laishui.Intelligent NURBS Interpolator Based on the Adaptive Feedrate Control[J].Chinese Journal of Aeronautics,2007,(20):469-474.
    [17]游有鹏,王珉,朱剑英.NURBS曲线高速高精度加工的插补控制[J].计算机辅助设计与图形学学报,2001,13(10):943-947.
    [18]X.Zhiming,C.Jincheng,F.Zhengjin.Performance Evaluation of a Real-Time Interpolation Algorithm[J].The International Journal of Advanced Manufacturing Technology,2002,20:270-276.
    [19]Hong-TzongYau,Ming-TzongLin,Meng-ShiunTsai.Real-time NURBS interpolation using FPGA for high speed motion control[J].Computer-Aided Design,2006,38:1123-1133.
    [20]K.K.Krishnan,J.kappen,B.Bahr.Calculation of variable feed rate and spindle speed for NURBS based CNC machining[J].Transactions of NAMRI/SME.2001,(24):429-435.
    [21]马朝阳,张承瑞.实时前瞻功能的NURBS动态插补算法[J].组合机床与自动化加工技术,2008(5):7-10.
    [22]Nam SH,Yang MY.A study on a generalized parametric interpolator with real-time jerk-limited acceleration[J].Computer-Aided Design,2004,36:27-36.
    [23]刘新山.NURBS曲线插补技术研究及其仿真[D].吉林:吉林大学,2007.
    [24]边玉超.自由曲线曲面CNC插补技术的研究[D].北京:北京化工大学,2004.
    [25]Syh-Shuih Yeh,Pau-Lo hsu.Adaptive-feed rate interpolation for parametric curves with a confined chord error[J].Computer Aided Design,2002,(34):229-237.
    [26]Meng-Shiun Tsai,Hao-Wei Nien,Hong-Tzong Yau.Development of an integrated look-ahead dynamics-based NURBS interpolator for high precision machinery[J].Computer-Aided Design.2008,5(40):554-566.
    [27]Ming-Tzong Lin,Meng-Shuin Tsai,Hong-Tzong Yau.Development of Real-time Look-Ahead Algorithm for NURBS Interpolator with Consideration of Servo Dynamics[C].IEEE Conference on Decision and Control,2007.12:1862-1867.
    [28]彭芳瑜,何莹,罗忠诚等.NURBS曲线机床动力学特性自适应直接插补[J].华中科技大学学报:自然科学版,2005,33(7):80-83.
    [29]陈金成,徐志明等.机床沿曲线高速加工时的运动学与运动学特性分析[J].机械工程学报,2002,38(1):31-34.
    [30]M.Weck,G.Ye.Sharp corner tracking using the KF control strategy[J].Annals of CIRP,1990,1(39):437-441.
    [3 1]彭芳瑜,何莹,李斌.NURBS曲线高速插补中的前瞻控制[J].计算机辅助设计与图形学学报.2006.5,15(5):625-629.
    [32]Jinho Park,Sungho Nam,Minyang Yang.Development of a real-time trajectory generator for NURBS interpolation based on the two-stage interpolation method [J].International Journal of Advanced Manufacture Technology,2005,26:359-365.
    [33]梁宏斌,王永章,李霞.自动调节进给速度的NURBS插补算法的研究与实现[J].计算机集成制造系统,2006.3,12(3):428-433.
    [34]Zhang Q,Greenway RB.Development and implementation of a NURBS curve motion interpolator[J].Robot Computer Integrated Manufacture,1998,14:27-36.
    [35]曹字男,王国苗等.插补前S加减速在CNC前瞻中的应用[J].北京航空航天大学学报,2007.5.33(5):594-599.
    [36]李建刚,张婷华等.一种完善的自适应NURBS曲线插补算法[J].中国机械工程,2008.5,19(9):1095-1098.
    [37]Xianbing Liu,Fahad Ahmad,kazoo yamazaki.Adaptive interpolation scheme for NURBS curves with the integration of machining dynamics[J].International Journal of Machine Tools & Manufacture,2005,45:433-444.
    [38]Qiyi G.Zhang,R.Bryan Greenway.Development and implementation of a NURBS curve motion interpolator[J].Robotics and Computer-Integrated Manufacturing,1998,14:27-36.
    [39]董伯麟,王治森,韩江.高速高精度加工中NURBS曲线混合插补算法[J].农业机械学报,2008.6,39(6):174-178.
    [40]Tikhon M,Ko TJ,Lee SH,Kim HS.NURBS interpolator for constant material removal rate in open NC machine tools[J].International Journal of Machine Tools and Manufacture,2004,(44):237-245.
    [41]Tae Jo Ko,Hee Sool Kim,Sung Ho Park.Macineability in NURBS interpolator considering constant material removal rate[J].International Journal of Machine Tools & Manufacture.2005,(45):665-671.
    [42]Farin G.Curves and surfaces for CAGD[M].USA:Morgan Kaufmann,2002.
    [43]Peigl L.Modifying the shape of rational B-splines,part 1:surfaces[J].CAD,1989,21(9).
    [44]张园,陈友东等.高速加工中连续微小线段的前瞻自适应插补算法[J].机床与液压,2008.6,36(6).
    [45]李有法.数值计算方法[M].北京:高等教育出版社,1996.
    [46]Yeh SS,Hsu PL.The speed-controlled interpolator for machining parametric curves[J].Computer-Aided Design,1999,31(5):349-357.
    [47]Daoshan Du,Yadong Liu,Cunliang Yan,Congxin Li.An accurate adaptive parametric curve interpolator for NURBS curve interpolation[J].The International Journal of Advanced Manufacturing Technology,2007,32:999-1008.
    [48]杜道山,燕存良,李从心.一种实时前瞻的自适应NURBS插补算法[J].上海交通大学学报,2006.5,40(5):843-847.
    [49]Tsehaw Yong,Ranga Narayanaswami.A parametric interpolator with confined chord errors,acceleration and deceleration for NC machining[J].Computer Aided Design,2003,35:1249-1259.
    [50]Tianmiao Wang,Yunan Cao,Youdong Chen.A New Feedrate Adaptation Control NURBS Interpolation Based on de Boor Algorithm in CNC Systems[C].American Control Conference,2008.6:4075-4080.
    [51]Tae Jo Ko,Hee Sool Kim,Sung Ho Park.Machineability in NURBS interpolator considering constant material removal rate[J].International Journal of Machine Tools & Manufacture,2005,45:665-671.
    [52]Hongyao Shen,Jianzhong Fu,Zichen Chen.Axis-based look-ahead interpolator for machining of surfaces represented by NURBS curves[J].Machining Science and Technology,2008,12(4):546-562.
    [53]任锟,傅建中,陈子辰.高速加工中速度前瞻控制新算法研究[J].浙江大学学报工学版,2006.11,40(11):1985-1988.
    [54]徐科军,张瀚等.TMS320X281xDSP原理与应用[M].北京:北京航空航天大学出版社,2006.
    [55]刘和平,张卫宁,刘林等.TMS320C28X系统DSP指令和编程指南[M].北京:清华大学出版社,2005.
    [56]叶佩青,汪劲松.MCX314运动控制芯片与数控系统设计[M].北京:北京航空航天大学出版社,2002.
    [57]韩安太,刘峙飞,黄海.DSP控制器原理及其在运动控制系统中的应用[M].北京:清华大学出版社,2003.
    [58]Chang Y F.Buffered DDA command generation in a CNC[J].Control engineering practice,2003,11:797-804.
    [59]任锟.高速数控加工的前瞻控制理论及关键技术研冤[D].浙江:浙江大学,2008.

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700