数控切绘系统曲线拟合及轨迹优化研究与应用
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摘要
数控切绘机是一种集数控技术、精密机械制造为一体的智能化数控加工设备,它的出现解决了手工艺品和模具加工生产效率低的问题。但是传统的切绘机可供利用的资源有限,加工的图形文件处理过程繁琐,因此在精度、效率方面难以达到较高要求。
本文深入研究了数控切绘机加工图形的整个过程,对控制系统的设计、图形的识别和加工轨迹等几个方面进行了研究,得出了以下结论:
(1)构建切绘机能易识别的图形文件。待加工的矢量化图形需要以线段或圆弧的形式来表达。首先运用曲线拟合,通过样条曲线的控制点找到图形轮廓上的矢量数据点,然后对轮廓上的点进行圆弧和线段的拟合,提出了采用模糊推理方法对曲线的拟合状态进行判定。
(2)优化加工轨迹。在数控加工中,路径的优化问题一般围绕着如何减少走刀空行程来考虑,其中就涉及到图形轮廓的加工顺序和各轮廓加工的起割点两个因素。在处理实际问题时,分别从刀切割轨迹和笔绘制轨迹两个方面着手。在刀切割轨迹的优化中,在考虑了内外层包含问题的前提要求下,将图形轮廓加工轨迹问题处理成旅行商问题,以遍历的方式寻找出各个轮廓之间的切割顺序,并配之以最近邻算法确定每个轮廓的起割点,最终确定轮廓的加工路径。在笔绘制轨迹的优化中,存在着闭合和不闭合的图形轮廓,使用最近距离算法来处理。
(3)切绘机控制系统采用基于LPC2138微处理器的μC/OS-II实时操作系统平台,合理、高效的完成各种任务的调配。结合一些外围控制模块,如电源控制系统、运动控制系统和通讯系统等。软件设计部分采用多任务方式进行系统程序的编写,使数控切绘机实现对加工图形稳定、高效的切割和绘制。并通过液晶屏显示控制的过程,给人以直观的感受。实现数控图形有效的切绘。
为了进一步提高切绘机的加工效率,本论文提出了在上述处理过程中存在的不足,还有许多问题值得继续研究。
Cutting machine is the intelligent CNC(Computer numerical control) processing equipment which integrated the digital control technology and precision machinery manufacturing, whose appearance greatly lighten the problem of low productivity on the craft and mold manufacture. However, the resource of the traditional cutting machine is limited, as well as the processing of graphics files process is quite fussy, so neither the accuracy nor the efficiency are difficult to achieve.
This paper is based on the whole process of CNC cutting machine dealing with graphics, which mainly focus on how to design control system, graphics identify, and process tracking. The following results have been reached:
Firstly, the project file that can be identified by CNC cutting machine is created. Vector graphics, to be processed, need to be expressed by line or arc. So a series of data points are sampled in the B-spline curve by the method of curve fitting, then arc and line fitting is conducted. In order to improve the cutting accuracy, fuzzy reasoning method is used to determine the state of curve fitting and determines the membership function based on lines and arcs.
Secondly, the process path is optimized. Reducing free travel is an effective way to achieve the optimal path, which related to two factors about the processing sequence of graphical contours and starting points of every contour. In the practice, the cutting path and drawing path are solved respectively. When cutting path is optimized, the graphical processing path problem is regarded as the traveling salesman problem after taking into account the contain problem of inner and outer layers. The processing sequence of graphical contours is found out by the way of traversal. And the nearest neighbor algorithm determines a starting point from each contour. So the processing path is also determined. When drawing path is optimized, the nearest neighbor algorithm is used to deal with closed and opened graphical contours.
Thirdly, the control system is based on LPC2138 microcontroller andμC/OS-II real-time operating system platform which carries on various tasks suitably. Some external control modules, such as power control systems, motion control systems and communications systems, construct the control system hardware design. Software adopts a multi-task system to write code, so the CNC cutting machine can cut and draw graphics stably and efficiently. And LCD screen displayer provides users with a good interactive mode of operation. The cutting of NC graphics can be realized.
To maximize the processing efficiency of cutting plotter, there are still a lot of shortcomings on the proposing of this article, also there are many topics awaiting us to carry out research in further.
本文深入研究了数控切绘机加工图形的整个过程,对控制系统的设计、图形的识别和加工轨迹等几个方面进行了研究,得出了以下结论:
(1)构建切绘机能易识别的图形文件。待加工的矢量化图形需要以线段或圆弧的形式来表达。首先运用曲线拟合,通过样条曲线的控制点找到图形轮廓上的矢量数据点,然后对轮廓上的点进行圆弧和线段的拟合,提出了采用模糊推理方法对曲线的拟合状态进行判定。
(2)优化加工轨迹。在数控加工中,路径的优化问题一般围绕着如何减少走刀空行程来考虑,其中就涉及到图形轮廓的加工顺序和各轮廓加工的起割点两个因素。在处理实际问题时,分别从刀切割轨迹和笔绘制轨迹两个方面着手。在刀切割轨迹的优化中,在考虑了内外层包含问题的前提要求下,将图形轮廓加工轨迹问题处理成旅行商问题,以遍历的方式寻找出各个轮廓之间的切割顺序,并配之以最近邻算法确定每个轮廓的起割点,最终确定轮廓的加工路径。在笔绘制轨迹的优化中,存在着闭合和不闭合的图形轮廓,使用最近距离算法来处理。
(3)切绘机控制系统采用基于LPC2138微处理器的μC/OS-II实时操作系统平台,合理、高效的完成各种任务的调配。结合一些外围控制模块,如电源控制系统、运动控制系统和通讯系统等。软件设计部分采用多任务方式进行系统程序的编写,使数控切绘机实现对加工图形稳定、高效的切割和绘制。并通过液晶屏显示控制的过程,给人以直观的感受。实现数控图形有效的切绘。
为了进一步提高切绘机的加工效率,本论文提出了在上述处理过程中存在的不足,还有许多问题值得继续研究。
Cutting machine is the intelligent CNC(Computer numerical control) processing equipment which integrated the digital control technology and precision machinery manufacturing, whose appearance greatly lighten the problem of low productivity on the craft and mold manufacture. However, the resource of the traditional cutting machine is limited, as well as the processing of graphics files process is quite fussy, so neither the accuracy nor the efficiency are difficult to achieve.
This paper is based on the whole process of CNC cutting machine dealing with graphics, which mainly focus on how to design control system, graphics identify, and process tracking. The following results have been reached:
Firstly, the project file that can be identified by CNC cutting machine is created. Vector graphics, to be processed, need to be expressed by line or arc. So a series of data points are sampled in the B-spline curve by the method of curve fitting, then arc and line fitting is conducted. In order to improve the cutting accuracy, fuzzy reasoning method is used to determine the state of curve fitting and determines the membership function based on lines and arcs.
Secondly, the process path is optimized. Reducing free travel is an effective way to achieve the optimal path, which related to two factors about the processing sequence of graphical contours and starting points of every contour. In the practice, the cutting path and drawing path are solved respectively. When cutting path is optimized, the graphical processing path problem is regarded as the traveling salesman problem after taking into account the contain problem of inner and outer layers. The processing sequence of graphical contours is found out by the way of traversal. And the nearest neighbor algorithm determines a starting point from each contour. So the processing path is also determined. When drawing path is optimized, the nearest neighbor algorithm is used to deal with closed and opened graphical contours.
Thirdly, the control system is based on LPC2138 microcontroller andμC/OS-II real-time operating system platform which carries on various tasks suitably. Some external control modules, such as power control systems, motion control systems and communications systems, construct the control system hardware design. Software adopts a multi-task system to write code, so the CNC cutting machine can cut and draw graphics stably and efficiently. And LCD screen displayer provides users with a good interactive mode of operation. The cutting of NC graphics can be realized.
To maximize the processing efficiency of cutting plotter, there are still a lot of shortcomings on the proposing of this article, also there are many topics awaiting us to carry out research in further.
引文
[1]李正义.基于ARM的数控切绘机控制系统研究与设计[D].湘潭大学,2007.
[2]李笑非.基于PowerPC FSC82大型绘图机控制系统的设计与实现[D].天津工业大学, 2005.
[3]陈雪梅.基于嵌入式系统的服装CAD绘图机的开发[D].天津工业大学,2003.
[4]石磊,张甲英,胡仲翔.Visual C++语言数控加工程序译码的实现方法[J].全国先进制造技术高层论坛暨制造业自动化信息化技术研讨会论文集,2007:342-344.
[5]胡国玉.基于数控加工图形数据处理方法的研究[D].新疆大学,2009.
[6]周江波.数控加工中图形文件的研究与仿真[D].南京理工大学,2009.
[7]王志成.数控原理与控制系统[M].国防工业出版社,2007.
[8]彭敏新.我国数控技术发展现状分析[J].中国集体经济,2007(6):159-160.
[9]陈苗荪.中国等离子弧切割机的现状及其分析[J].焊接切割论坛,2006(9):23-25.
[10] A. Ferrolho, M. Crisostomo, M. Lima. Intelligent control software for industrial CNC machines[J].Intelligent Engineering Systems,2005.
[11]王子菡.数控平板式高精度切绘机的设计[D].湘潭大学, 2004.
[12] Chiang L E, Ramos J. CNC Control of A Laser Cutting Machine[J]. Industrial Electronics, 1994,25(27):236- 241.
[13] Amold Berger著,吕骏译.嵌入式系统设计Embedded System Design An Introduction to processes, Tools and Techniques[M].电子工业出版社,2002.
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[15]王敏,邵定宏.图形文件格式兼容性研究与实现[J].计算机工程与设计,2007, 28(15): 3758-3760.
[16] W B Lee, D Dao, J G Li. An NC Tool Path Translator for Vital Machining of Precision Optical Products[J]. Journal of Materials processing Technology, 2003(140):211-216.
[17] Dorigo M, Maniezzo V, Colorni A. The ant system optimization by a colony of cooperating agents[J]. IEEE Transactions on Systems, Man, and Cybernetics Part B,1996,26(1):l-13.
[18]刘会霞,王霄,蔡兰.钣金件数控激光切割割嘴路径的优化[J].计算机辅助设计与图形学学报,2004, 16(5): 660- 665.
[19]梁吉元,郁鼎文,张玉峰等.CAM系统中孔加工的优化处理[J].计算机集成制造系统,2000,6(1):120-124.
[20]龚清洪.基于DXF的绘图轨迹优化及仿真系统研究与实现[D].西北工业大学,2006.
[21]余国兴,玉成,李涤尘.平面多轮廓加工路径优化模型及其近似算法[J].西安交通大学机械工程学院,2004.
[22] Steve Krar Arthur Gill. Computer Numerical Control Programming Basics[M]. New York: INDUSTRIAL PRESS INC, 1999:15-17.
[23]王维.基于CAD文件的直角坐标机械手绘图算法的研究[D].哈尔滨工业大学,2007.
[24]张金萍,倪洪启,罗鹏.DXF接口文件在复杂图形数控加工中的应用[J].沈阳化工学院学报,2004,18(2):154-155.
[25]孙家广.计算机图形学[M].清华大学出版社,2004.
[26] Qu Jun, Shun Ye, Qu Gang. Non-linear curve approximation using integral b-splines. Machinery Design & Manufacture, 2001, 10(5):36-37.
[27] Park H, Lee J H. B-spline curve fitting based on adaptive curve refinement using dominant points [J]. Chosun University, 2006, 39 (6): 439-451.
[28]陈守年.基于运动控制卡的三次B样条曲线插补的分析及实现[D].中国科学技术大学,2009.
[29] Teh C H, Chin R T. On the detection of dominant points on digital curves[J]. IEEE Pattern Anal. Mach. Intell, 1989(11): 859-872.
[30] Pei S C, Horng J H. Fitting digital curves using circular arcs[J].Pattern Recognition. 1995(28):107-116.
[31] Horng J H, Li J T.A dynamic programming approach for fitting digital planer curves with line segments and circular arcs[J]. Pattern Recognition Lett, 2001(22):183-197.
[32]姚必强,姚进.数控加工曲线的等弧长圆弧拟合方法[J].四川大学学报, 2008(40):171-174.
[33]汤兵勇,路林吉,王文杰.模糊控制理论与应用技术[M].清华大学出版社,2002.
[34] K.Asai. Fuzzy System for Management translate by Charles Aschmann Ohmsha[J]. IOS Press,2001:51-55.
[35]李士勇.模糊控制,神经控制和智能控制论[M].哈尔滨工业大学出版社,1998.
[36] Liu K F, Yu C W. Integrating case-based and fuzzy reasoning to qualitatively predict risk in an environmental impact assessment review[J]. Environmental Model & Software, 2009(24):1241-125.
[37]李文.基于类高斯隶属函数的自适应模糊推理建模研究[J].科学技术与工程,2010(6): 1433-1437.
[38]陈铭,李红燕,王铁宁.模糊综合评判中非线性隶属函数的确定[J].数学的实践与认识,2006(36):124-128.
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[42]季国顺,王文,陈子辰.数控多轮廓加工走刀空行程路径优化[J].农业机械学报,2008,154-158.
[43]李泳,张宝峰.复杂轮廓激光切割路径优化算法的研究[J].天津理工大学学报,2007,76-79.
[44]王晓东.算法设计与分析[M].清华大学出版社,2003.
[45]余国兴,丁玉成,李涤尘.平面多轮廓加工路径优化模型及其近似算法[J].西安交通大学学报,2004, 38 (1):39-43.
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[52] Jean J.Labrosse著,邵贝贝译.嵌入式实时操作系统μC/OS-II[M].北京航空航天大学出版社,2003.
[2]李笑非.基于PowerPC FSC82大型绘图机控制系统的设计与实现[D].天津工业大学, 2005.
[3]陈雪梅.基于嵌入式系统的服装CAD绘图机的开发[D].天津工业大学,2003.
[4]石磊,张甲英,胡仲翔.Visual C++语言数控加工程序译码的实现方法[J].全国先进制造技术高层论坛暨制造业自动化信息化技术研讨会论文集,2007:342-344.
[5]胡国玉.基于数控加工图形数据处理方法的研究[D].新疆大学,2009.
[6]周江波.数控加工中图形文件的研究与仿真[D].南京理工大学,2009.
[7]王志成.数控原理与控制系统[M].国防工业出版社,2007.
[8]彭敏新.我国数控技术发展现状分析[J].中国集体经济,2007(6):159-160.
[9]陈苗荪.中国等离子弧切割机的现状及其分析[J].焊接切割论坛,2006(9):23-25.
[10] A. Ferrolho, M. Crisostomo, M. Lima. Intelligent control software for industrial CNC machines[J].Intelligent Engineering Systems,2005.
[11]王子菡.数控平板式高精度切绘机的设计[D].湘潭大学, 2004.
[12] Chiang L E, Ramos J. CNC Control of A Laser Cutting Machine[J]. Industrial Electronics, 1994,25(27):236- 241.
[13] Amold Berger著,吕骏译.嵌入式系统设计Embedded System Design An Introduction to processes, Tools and Techniques[M].电子工业出版社,2002.
[14]李祥友,曾晓雁.常用图形文件格式浅析[J].微型机与应用,2001 (9):57-58.
[15]王敏,邵定宏.图形文件格式兼容性研究与实现[J].计算机工程与设计,2007, 28(15): 3758-3760.
[16] W B Lee, D Dao, J G Li. An NC Tool Path Translator for Vital Machining of Precision Optical Products[J]. Journal of Materials processing Technology, 2003(140):211-216.
[17] Dorigo M, Maniezzo V, Colorni A. The ant system optimization by a colony of cooperating agents[J]. IEEE Transactions on Systems, Man, and Cybernetics Part B,1996,26(1):l-13.
[18]刘会霞,王霄,蔡兰.钣金件数控激光切割割嘴路径的优化[J].计算机辅助设计与图形学学报,2004, 16(5): 660- 665.
[19]梁吉元,郁鼎文,张玉峰等.CAM系统中孔加工的优化处理[J].计算机集成制造系统,2000,6(1):120-124.
[20]龚清洪.基于DXF的绘图轨迹优化及仿真系统研究与实现[D].西北工业大学,2006.
[21]余国兴,玉成,李涤尘.平面多轮廓加工路径优化模型及其近似算法[J].西安交通大学机械工程学院,2004.
[22] Steve Krar Arthur Gill. Computer Numerical Control Programming Basics[M]. New York: INDUSTRIAL PRESS INC, 1999:15-17.
[23]王维.基于CAD文件的直角坐标机械手绘图算法的研究[D].哈尔滨工业大学,2007.
[24]张金萍,倪洪启,罗鹏.DXF接口文件在复杂图形数控加工中的应用[J].沈阳化工学院学报,2004,18(2):154-155.
[25]孙家广.计算机图形学[M].清华大学出版社,2004.
[26] Qu Jun, Shun Ye, Qu Gang. Non-linear curve approximation using integral b-splines. Machinery Design & Manufacture, 2001, 10(5):36-37.
[27] Park H, Lee J H. B-spline curve fitting based on adaptive curve refinement using dominant points [J]. Chosun University, 2006, 39 (6): 439-451.
[28]陈守年.基于运动控制卡的三次B样条曲线插补的分析及实现[D].中国科学技术大学,2009.
[29] Teh C H, Chin R T. On the detection of dominant points on digital curves[J]. IEEE Pattern Anal. Mach. Intell, 1989(11): 859-872.
[30] Pei S C, Horng J H. Fitting digital curves using circular arcs[J].Pattern Recognition. 1995(28):107-116.
[31] Horng J H, Li J T.A dynamic programming approach for fitting digital planer curves with line segments and circular arcs[J]. Pattern Recognition Lett, 2001(22):183-197.
[32]姚必强,姚进.数控加工曲线的等弧长圆弧拟合方法[J].四川大学学报, 2008(40):171-174.
[33]汤兵勇,路林吉,王文杰.模糊控制理论与应用技术[M].清华大学出版社,2002.
[34] K.Asai. Fuzzy System for Management translate by Charles Aschmann Ohmsha[J]. IOS Press,2001:51-55.
[35]李士勇.模糊控制,神经控制和智能控制论[M].哈尔滨工业大学出版社,1998.
[36] Liu K F, Yu C W. Integrating case-based and fuzzy reasoning to qualitatively predict risk in an environmental impact assessment review[J]. Environmental Model & Software, 2009(24):1241-125.
[37]李文.基于类高斯隶属函数的自适应模糊推理建模研究[J].科学技术与工程,2010(6): 1433-1437.
[38]陈铭,李红燕,王铁宁.模糊综合评判中非线性隶属函数的确定[J].数学的实践与认识,2006(36):124-128.
[39] David S.Johnson, Lyle A.McGeoch. The Traveling Salesman Problem: A Case Study in Local Optimization,In: EHL Aarts, JK Lenstraeds. Local Search in Optimization[J]. NewYork: Tohn Wiley and Sons, 1997,215-310.
[40] Grotschel M, Holland A. Solution of large-scale symmetric traveling salesman Problems[J]. Mathematical Programming, 1991,51(2):141-202.
[41]龚清洪.基于DXF的绘图轨迹优化及仿真系统研究与实现[D].西北工业大学,2006.
[42]季国顺,王文,陈子辰.数控多轮廓加工走刀空行程路径优化[J].农业机械学报,2008,154-158.
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