亚洲免费av电影一区二区三区,日韩爱爱视频,51精品视频一区二区三区,91视频爱爱,日韩欧美在线播放视频,中文字幕少妇AV,亚洲电影中文字幕,久久久久亚洲av成人网址,久久综合视频网站,国产在线不卡免费播放

        ?

        Roundness error evaluation by minimum zone circle via microscope inspection

        2013-11-05 07:30:46JIANGLi姜黎ZHANGZhijing張之敬WUWeiren吳偉仁JINXin金鑫JIEDegang節(jié)德剛
        關(guān)鍵詞:金鑫

        JIANG Li(姜黎), ZHANG Zhi-jing(張之敬), WU Wei-ren(吳偉仁),,JIN Xin(金鑫), JIE De-gang(節(jié)德剛)

        (1.School of Mechanical and Vehicular Engineering,Beijing Institute of Technology,Beijing 100081,China;2.Lunar Exploration and Aerospace Engineering Center,Beijing 100037,China)

        Micro parts are widely used in aerospace,micro-electro-mechanical systems(MEMS)and other fields.The technology development establishes stricter standards for functionalities,performances and reliability ofthe micro parts.Therefore,the precision detection technologies for micro parts with geometric parameters within the range of 0.01-10 mm have attracted more researchers’attentions throughout the world.Because the microscope method assisted with precise displacement of mechanical platform possesses higher inspection efficiency than other inspection method,e.g.universal tool measuring microscope and coordinate measurement machine,it has been widely used in precision measurement of micro parts[1].

        Since micro-edges of the micro part are complex,measurements of different data fitting methods are distinguished for the same geometric parameter[2-3].This exerts significantly negative influences on the quality judgment for micro parts.For the roundness error evaluation,the minimum zone circle(MZC)method meets the minimum condition and can be used to obtain the minimum evaluation result which is the minimum radius difference between two concentric circles that enclose all data points.And therefore,the MZC method has caught the researchers’attention[4-5].Up to date,scholars throughout the world have conducted a substantial number of researches on the MZC method and proposed many optimization algorithms[6-9].For evaluating the roundness error,these algorithms have to do a great amount of computations.This limitation makes these algorithms inapplicable to the practical engineering measurement.In recent years,for reducing computation complexity the convex hull theory has been applied to evaluating form errors[10-11].In this paper,the convex hull will be used to develop an improved algorithm of MZC(IMZC)for evaluating the roundness errors of micro parts.

        1 Evaluation of roundness error via MZC

        For discrete measurement,the roundness error is defined as the minimum radial separation between two concentric circles that enclose all data points from the circle contour[12].For evaluating roundness errors,there are four common methods,i.e.least square circle(LSC),minimum circumscribed circle(MCC),maximum inscribed circle(MIC)and MZC.According to the definition,MZC yields the smallest zone than other methods,and thus obtains the minimum radial separation between two circles which enclose all points of the profile[13],as shown in Fig.1.

        Fig.1 Concentric circles of minimum zone

        The MZC roundness error evaluation takes the“2+2”model.It means that the four tangent points are used to construct two concentric circles,i.e.the maximum and the minimum circles which all data points lie on or inside and whose radius distance takes the minimum value.The MZC roundness error,fMZC,is measured with the minimum radius distance,rmax- rmin,where rmaxis the radius of the maximum circle and rminis the radius of the minimum circle.The distribution of the four tangent points takes two forms,the highlow-high-low and low-high-low-high,as shown in Fig.2.

        Fig.2 Model of MZC

        Therefore,an important step for evaluating roundness errors of micro parts is to find the two concentric circleswhich enclose allsampling points of the contour.According to the above analysis,the key to the step is to find four tangent points,two on the maximum circle and the other two on the minimum circle.

        2 Improved algorithm of MZC via convex hull

        According to the above analysis,the key to the roundness error evaluation via MZC is to determine two concentric circles with the minimum radius difference which enclose allsampling points of the contour.According to the criteria for the two circles,two tangent points on the maximum circle are on the circumscribed convex polygon of the sampling points.Thus,once the circumscribed convex polygon is determined,it is easy to find these two tangent points.The determination of the circumscribed convex polygon can be done with a convex hull algorithm.After processing the sampling points p of the contour,two point sets,pMCCand pMIC,will be available,where pMCCis a convex set for finding two tangent points on the maximum circle and pMICis a non-convex set for finding the other two tangent points on the minimum circle.Based on these four tangent points,the roundness error evaluation via MZC can be done easily.

        2.1 Processing the contour points via convex hull

        The convex hull definition:

        Given a set S={s1,s2,…,sN}of points in the plane,the convex hull conv(S)is the smallest convex polygon in the plane that encloses all points in the set S[14].The key to determining the convex hull for the set S is to find some points which construct the convex hull.These points are called the convex points.

        Procedures for finding the vertexes of the convex hull are as follows:

        Step 1Sorting the contour points

        For a given set of data points Q,let c be the point in Q with the minimum y-coordinate,or the leftmost such point in case of a tie.The remaining points in Q are sorted in the counterclockwise order by polar angles between the x-axis and the vector linking the points c and qito construct a new point set P={pi|pi=(xi,yi),i=1,2,…,n},wherein xi,yiare the coordinates of the point pi.

        Step 2Judgment of the vertexes of the convex hull

        Let c be an index to the newly found convex point.According to the first step,the first point in P is a convex point.Thus,at the beginning,c is equal to 1.For the ithpoint piin the point set P(1 < i < n),calculate the value of s(pc,pi,pi+1)as

        If s(pc,pi,pi+1)is larger than 0,piis a convex point and let c take the value of i.Otherwise,piis not a convex point and remove this point from the point set P.If i is equal to n-1,all points in P are convex points.Otherwise,add 1 to i and according to the above process check whether this new ithpoint piis a convex point.This calculation and check process will be completed for every point in the point set P(1<i<n).

        According to the above procedure,many algorithms have been developed since the 70’s of the last century.The typical algorithms included Graham Scan,Gift Wrapping,the“divide-andconquer”algorithm and so on[15].Since the computational complexity of Graham Scan achieves the lower limit O(nlog n)[16],Graham Scan algorithm is adopted for the roundness error evaluation to sort the contour points into two point sets,pMCCand pMIC,where pMCCis the set of circumscribed circle points and pMICis the set of inscribed circle points.Flow chart of this algorithm is shown in Fig.3.

        Fig.3 Contour point processing flow chart

        2.2 Determination of four tangent points

        There are two steps to find the four tangent points from these two data point sets of pMCCand pMIC.The first step is to determine two or three vertexes on the minimum circumscribed circle and to store these vertexes in a point set VMCC.Determining two or three vertexes on the maximum inscribed circle is also included in the first step.These vertexes on the maximum inscribed circle are stored in another point set of VMIC.It must be noted that the sizes of these two sets,VMCCand VMIC,cannot contain two points as the same time.The detailed information about how to determine vertexes from pMCCand pMICare discussed by Jywe W.et al[17].Based on the relationship between the MZC,the maximum inscribed circle and the MZC[17-18],the second step is to find the four tangent points,two from VMICand two from VMCC.The procedure for determining these four tangent points is illustrated in Fig.4.

        Fig.4 Four tangent points determination algorithm

        2.3 Calculation of roundness error

        Using the four determined tangent points,the center of the minimum zone reference circles is found as shown in Fig.5.In Fig.5,L1is a straight line through tangent points of b and d on the outer minimum zone reference circle and L2is a straight line through tangent points of a and c on the inner minimum zone reference circle.L3and L4are perpendicular lines to L1and L2,respectively.These two perpendicular lines have slopes of k1and k2.Calculate the reference circle center,(cx,cy),as follows:

        where(xm1,ym1)is the middle point between b and d,and(xm2,ym2)the middle between a and c.

        Fig.5 Four tangent points of MZC

        After determining the reference circle center,the radius,rmax,of the outer minimum zone reference circle is equal to the distance between the center and b or d,and the radius,rmin,of the inner minimum zone reference circle is the distance between the center and a or c.At this stage,the roundness error,fMZC,via MZC is evaluated as the difference between rmaxand rmin

        3 Performance analysis

        To verify the accuracy and efficiency of the IMZC,in this section,measurements of a cylindrical part produced by the turning operation and the center hole of two fine-pitch gears is used.The roundness error evaluation results via IMZC,MZC and LSC is analyzed.

        3.1 Evaluation result analysis for cylindrical part by turning operation

        The contour of the turning cylindrical part with the radius of 15 mm is measured with Mitutoyo Roundness Measuring Equipment RA-2100.Due to the extremely large volume of measured contour points,the original measurements are sampled according to the uniform distribution rules.The sample size is 40.The sampled contour points are listed in Tab.1.Using these sample points,the roundness error for this turning cylindrical part is assessed with LSC,IMZC and the traditional MZC.The assessment results via LSC and IMZC are listed in Tab.2,and the results via MZC and traditional MZC in Tab.3.

        Tab.2 shows that the roundness error via LSC is 0.027 0 mm,whereas the roundness error via IMZC 0.0251 mm.From the set of data,IMZC has higher precision than LSC.

        Tab.1 Sample contour points mm

        Tab.2 Evaluation result via LSC and IMZC mm

        Tab.3 Evaluation result via IMZC and MZC

        From Tab.3,we can see that IMZC has the same evaluation results with the traditional MZC.The computation time for IMZC by incorporating Graham’s scan convex hull algorithm is less than 10%of the traditional MZC and thus the roundness error evaluation has obtained about 10 efficiency gains.

        3.2 Evaluation result analysis for the hole center of fine-pitch gears

        Images of these two fine-pitch gears were obtained with a micro-vision inspection and an inspection software code by the authors as shown in Fig.6.The contour points of these two gears were measured via an edge detection algorithm,which is implemented and incorporated into the inspection software.These contour point measurements are evaluated and the roundness error evaluation results are list in Tab.4.These figures in Tab.4 verify the practicability and reliability of IMZC.

        Fig.6 Image of fine-pitch gear

        Tab.4 Evaluation result of roundness error evaluation for two fine-pitch gears mm

        4 Conclusion

        In this paper,using the convex hull algorithm,an improved algorithm of MZC(IMZC)method was developed for evaluating roundness errors of micro parts.IMZC is simple and can be implemented easilyviacomputer programming languages.It can assess roundness errors according to contour point measurements in rectangular and polar coordinate system.The performance of IMZC was analyzed according to contour point measurements of a cylindrical part produced by the turning operation and the center hole of finepitch gears.The analysis results showed that IMZC had the same precision with the traditional MZC and higher precision than least squares circle(LSC).The results showed that the computation time of IMZC is just 6.89%of traditional MZC,demonstrating the high efficiency of the IMZC.

        [1] Wang Xiangjun,Wang Feng.Study of micro mechanical size inspection technology by microscope precision digital image[J].Optics and Precision Engineering,2001,19(6):511-513.(in Chinese)

        [2] Zhang Zhijing,Du Fang,Jin Xin,et al.Complex edge recognition algotithm of micro-accessory[J].Optics and Precision Engineering,2009,17(2):355-361.(in Chinese)

        [3] Zhang Lin,Zhang Zhijing,Jin Xin,et al.Study on measuring algorithms of geometry in microscope inspection method[J].Tool Engineering,2009,43(10):88-91.(in Chinese)

        [4] Zheng Xiang,Ruan Zhiqiang,Xia Weiming.Minimum circum scribed circle finite element post-processing algorithm for coaxial error[J].Journal of Southeast University,2009,39(6):1156-1160.(in Chinese)

        [5] Liu Fei,Liang Lin,Peng Xiaonan.Evaluating and application algorithm of minimum zone circle for roundness error in cartesian coordinate system[J].Tool Engineering,2011,45(5):87 -90.(in Chinese)

        [6] Zhang Tieying,Lai Kewei.Study on computational geometry approaches to assessing roundnes[J].Journal of Engineering Graphics,2002(3):145 -153.(in Chinese)

        [7] Yue Wuling,Wu Yong.Roundness error based on quasi-incremental algorithm[J].Chinese Journal of Mechanical Engineering,2008,44(1):87-91.(in Chinese)

        [8] Cui Changcai,Che Rensheng,Ye Dong.Circularity error evaluation using genetic algorithm[J].Optics and Precision Engineering,2001,9(6):499 - 505.(in Chinese)

        [9] Andrea R,Matteo A,Barloscio Matteo B,et al.Fast genetic algorithm for roundness evaluation by the minimum zone tolerance(MZT)method[J].Measurement,2011,44(7):1243 -1252.

        [10] Lee M K.An enhanced convex-hull edge method for flatness tolerance evaluation[J].Computer-Aided design,2009,41(12):930 -941.

        [11] Li Xiuming,Shi Zhaoyao.Development and application of convex hull in the assessment of roundness error[J].Machine Tools and Manufacture,2008,48(1):135-139.

        [12] He Yongxin,Wu Chongpei.Geometry presion criterion[M].Beijing:Beijing Institute of Technology Press,2003:35-37.(in Chinese)

        [13] Ni Xiaohua.Evaluation of form error and measurement uncertainty[M].Beijing:Chemical Industry Press,2008:20-45.(in Chinese)

        [14] Zhou Wenke.An accelerating algorithm for computing convex hull of simple polygon[J].Journal of Guangzhou University:Natural Science Edition,2003,2(6):546-547.(in Chinese)

        [15] de Berg M,van Kreveld M.Computional geometry:algorithm and applications[M].Beijing:Tsinghua University Press,2009:3 -10.

        [16] Yao A C.A lower bound to finding convex hulls[J].Journal of the ACM,1981,28(4):780-787.

        [17] Jywe Wenyuh,Liu Chienhong,Chen Cha'okuang.The min-max problem for evaluating the form error of a circle[J].Measurement,1999,26(4):273 -282.

        [18] Li Xiuming,Shi Zhaoyao.The relationship between the minimum zone circle and the maximum inscribed circle and the minimum circumscribed circle[J].Precision Engineering,2009,33(3):284-290.

        猜你喜歡
        金鑫
        First principles study of hafnium intercalation between graphene and Ir(111)substrate
        好朋友的話,吵架也沒關(guān)系
        Electronic structures of vacancies in Co3Sn2S2*
        電廠熱工控制系統(tǒng)中抗干擾技術(shù)運(yùn)用分析
        金鑫:保證乘客安全、貨物安全,是中國(guó)鐵路的自信
        中華兒女(2020年22期)2020-02-09 03:02:34
        闖入你的特立獨(dú)行
        “視光師金小鑫”其人
        ——專訪淮南壽陽(yáng)眼鏡總經(jīng)理金鑫
        雙魚鑰匙扣
        High-precision method of detecting motion straightness based on plane mirror interference
        Fuzzycontrol method to minimize the needle deflection duringneedle insertion therapy
        免费做爰猛烈吃奶摸视频在线观看| 日韩在线一区二区三区中文字幕| 国产精品自产拍在线18禁| 成年美女黄网站色大免费视频| 激情伊人五月天久久综合| 激情综合一区二区三区| 国产美女在线精品亚洲二区| 精品久久久久久99人妻| 国内精品少妇久久精品| 久久精品av在线观看| 中文字幕无码av波多野吉衣| 人禽伦免费交视频播放| 国产在线观看黄| 黑人一区二区三区啪啪网站| 男女激情视频网站在线| 国产精品一区二区av麻豆| 久久国产精品精品国产色婷婷| 乱伦一区二| 一区二区三区在线观看日本视频| 日本一区二区三区丰满熟女| 亚洲综合国产成人丁香五月激情| 中文字幕+乱码+中文字幕一区| 久久中文字幕无码一区二区| 亚洲视频不卡免费在线| 久久久精品国产免费看| 亚洲av无码国产综合专区| 国产精品麻豆成人av电影艾秋| 2021精品综合久久久久| 亚洲女同高清精品一区二区99| 青青草大香蕉视频在线观看| 色妞色视频一区二区三区四区 | 久久狼精品一区二区三区| 久久天天躁狠狠躁夜夜avapp| 永久免费不卡在线观看黄网站| 亚洲一区二区情侣| 黄片国产一区二区三区| 很黄很色很污18禁免费| 夜夜嗨av一区二区三区| 午夜无码片在线观看影院y| 日韩av一区二区蜜桃| 成年免费a级毛片免费看|