NGHIEN cufu - TRAO D 6 |
^fAOT SO KY THUAT PHAT HIEN BIEN TRONG X l / LY ANH AP DUNG CHO XAY DliNG M 5 HINH PROFILE BE MAT CHI TIET
SOME ri'.CHNlCAL FINDINGS IN BORDER PHOTO PROCESSING APPLICATION FOR BUILDING MODELS SURFACE PROFILE DETAILS
Nguyen Hoang Tung ' S Nguyin Thi PhflOng Mai S Nguyin Van Vinh^
'X'ien (.ong ngiie Tdng cue Cdng nghiep Qudc phdng - Bd Qudc phdng
"I'rfldng Dai hpc Bach khoa Hd Npi
TOM TAT
Ky thuat dd bien Id bdi todn mdi chi xuat hien each day khdng Idu, chi khodng vdi thap nien, nhUng da cd rat nhieu nghien cUu ve vdn de ndy. Bdi todn phdt hien bien ndi chung vdphdt hien bien chi tiet sau khi gia cdng tren mdy cat got CNC tai mot do cao tUdng doi z ndi rieng la vdn de chii yeu trong phdn tich dnh, vi cdc dac diem trich chon trong qud trinh phdn tich dnh chii yeu dUa vdo hien. Diem
bien Id mot diem md d dd cd sU thay doi dot ngdt ve mUc xdm. Tap hdp cdc diem bien tao thdnh hien hay dudng bao cua dnh. Tren cd sd dd ngUdi ta thUdng sU dung hai phUdngphdp phdt hien bien co dien vd phdt hien bien ndng cao. TU bien dang dUdc bieu dien d nhUng do cao z khdc nhau, ta se md td dUdc be
mat chi tiet sau gia cdng cd khi trong dd the hien dUdc do cao te'vi, hinh ddng be mat vd nep diitgdy tren be mat chi tiet.
TU khda: bien, phdt hien bien dnh, bieu dien bien dnh
ABSTRACT
Edge detection technique appeared only a few decades ago, hut has a lot of research on this is- sue. The problem of general edge detection and edge detection information after manufacturing on CNC machine at z height is relative major problem in image analysis, because of the features extracted in the process of selecting image analysis is based on the minutes. Border point, which has the sudden change
of gray level. The set of boundary points forms the boundary or boundaries of the image. Basis, Base on these concepts, two methods of classical edge detection and edge detection enhancement were used. From the boundary as shown in the different height z, the detailed surface after machining in which show high microstructure, surface appearance and fracture patterns on the surface...were described.
Keywords: edge, edge detection image, edit images perform
9 TAP CHI CO KHI VIET NAM • Sd 12 (Thang 12 nam 2011)
NGHIEN cufu - TRAO D(!)l
l.GIOfl THIEU phflpng phap Laplace
Trong cdng nghe che tao may, chi tiet ca 2.1.2. PhUdng phdp phdt hien bien gidn tiep khi sau gia cdng tren may cat gpt CNC ngodi dp
chinh xac kich thflde, hinh dang vd vi tri tflOng Ld qud trinh phan vflng dfla vdo phep xfl quan thi profile be mat ddng mpt vai trd quan ly ket cau ddi tflpng, cu the la dfla vdo sfl bien trpng; ddi khi profile be mat Id yeu td quyet dinh thien nhd vd ddng deu dp sdng cua cdc diem dnh den chat Iflpng vd gid tri cfla chi tiet do nd dnh thudc mpt ddi tflpng. Neu cdc vflng cua anh dxiac hfldng tdi dung sai, tinh bdi trpn, kha nang chiu xdc dinh thi dfldng phan ranh gifla cac vung dd mdi mdn vd tudi thp. chinh Id bien anh can tim. Viec phat hien bien vd phan vung ddi tflpng Id hai bdi todn ddi ngau.
Profile be mat chi tiet thfldng ddng thdi Tfl phat hien bien ta cd the tien hdnh phan Idp ton tai ba loai sai lech: sai lech hinh dang, sdng vd ddi tflpng, nhfl vay Id da phan vung dflpc anh. Vd nhdm be mat. Sai lech hinh dang la sai lech cfla be ngflpc lai, khi da phan vung dflpc dnh nghia Id da mat sau gia cdng so vdi be mat danh nghia tren phan lap dflpc thdnh cdc ddi tflpng, tfl dd cd the ban ve thiet ke; sdng be mat thfldng cd dang tuan phat hien dflpc bien can tim.
hodn theo chu ky; nhdm be mat Id thdnh phan sai
lech nhd nhat gay ra bdi qua trinh gia cdng cdn Tuy nhien, phflong phap tim bien trflc tiep tdn tai tren be mat chi tiet. Cdc thdnh phan sai thfldng sfl dung cd hieu qua vi it chiu anh hfldng lech hinh dang, sdng hay nhdm thfldng khdng cfla nhieu. Song neu sfl bien thien dp sdng cua xuat hien rieng le ma chflng ddng thdi tdn tai tren dnh Id khdng cao thi khd cd the phdt bien dflpc be mat chi tiet. Do dd viec xay dflng md binh pro- bien, trong trfldng hpp ndy viec tim bien theo file be mat thflc cua chi tiet sau gia cdng tren mdy phflpng phap trflc tiep td ra khdng dat dflpc bieu cat gpt CNC Id can thiet; khi dd ta se xdc dinh qua tdt. PbflPng phap tim bien gian tiep dfla tren dflpc nhdm, sdng hay sai lech hinh dang tuy vdo cdc vung, ddi hdi dp dung ly thuyet ve xfl ly ket muc dich cu the. Ndi dung chinh cfla bdi bdo Id cau ddi tflpng phflc tap, vi the khd cdi dat, song trinh bdy cac phflOng phdp phdt hien bien dang dat hieu qua cao khi sfl bien thien ve cfldng dp dnh be mat chi tiet sau gia cdng tren mdy cat gpt sang Id nhd.
CNC quan sat dflpc tren kinh hien vi cd dp phdng
dai cao. 2.1.3. Quy trinh phdt hien bien
2. MOT SO KY THUAT P H A T HIEN BIEN Bflde 1: Do dnh ghi dflpc thfldng cd nhieu, bflde mpt Id phdi Ipc nhilu
2.1. Cac phflong phap phat hien bien co dien
Bflde 2: Ldm ndi bien sfl dung cdc toan tfl 2.1.1. PhUdngphdp phdt hien bien trtic tiep phdt hien bien.
Phflong phdp phat hien bien ndy nham Bflde 3: Dinh vi bien. Chfl y rang ky thuat ldm ndi bien dfla vdo sfl bien thien ve gia tri dp ndi bien gay tdc dung phu Id gay nhieu ldm mot sd sang cua diem anh. Ky thuat chu yeu dung phat bien gia xuat hien do vay can loai bd bien gia.
hien bien d day la ky thuat dao hdm.
Bflde 4: Lien ket vd trich chpn bien.
Neu lay dao ham bac nhat cua dnh ta cd
phflong phap Gradient. PhflOng phap ndy bao 2.2. Cac phflOng phap phat hien bien nang cao gdm ky thuat gradient vd ky thuat la bdn.
2.2.1. PhUdngphdp Canny Neu lay dao hdm bac hai cua anh ta cd
TAP CHI CO KHI VIET NAM •t* So 12 (Thang 12 nam 2011)
NGHIEN cufu-TRAO D 6 |
Phflpng phdp ndy do John Canny d phdng thi nghiem MIT khdi xfldng vdo nam 1986. Can- ny da dfla mpt tap hpp cac rang budc md mpt phflOng phap phdt hien bien phai dat dflpc. Ong da trinh bay mpt phflOng phap tdi flu nhat de thflc hien dflpc cdc rdng bupc dd, phflpng phdp ndy dflpc gpi Id phflpng phap Canny.
2.2.2 PhUdngphdp Shen Castan
Shen va Castan cd cung quan diem vdi Canny ve mpt mau chung trong viec tdch cdc dfldng bien. Dd Id: nhan xoan dnh vdi mpt mat na ldm min, sau dd tim ra diem bien. Tuy nhien, Shen vd Castan lai khdng de cap den viec thuat todn se nban ra dflpc nhieu canh trong khi chi cd mpt canh tdn tai.
2.2.3. Phdt hien bien dUa vdo Wavelet
PhflOng phdp ndy sfl dung bien ddi Wavelet rdi rac (DWT) de phan tich anh thdnh nhieu dnh
cd dac diem vd xap xi.
3. T H V C N G H I $ M
Di kiim chflng tinh kha thi cua nhflng ky thuat phdt hien bien neu tren, chung tdi da chiip 50 dnh d cdc dO cao khdc nhau cua be mat chi tiet sau nguyen cdng phay tren may phay CNC bang kinh hien vi KEYENCE VHXIOO vdi dp phdng dai 450 lan. Be mat cua chi tiet dxiac tao ra vdi dao cat vd che dp cat nhfl sau: Dao phay hinh gdc 60°, phay sau 0,5 mm; bflde cat 0,5 mm; chieu sau cat Id 0,1 mm.
Vdi hi mat da cho d tren, chia thanh 50 lat cat song song cdch nhau 0,01 mm, vi tri lat cat dau tien Id mat phang di qua ddy cua gdc 60° tren be mat. Tai mat cat thfl 1 ta cd giao cua be mat chi tiet vdi mat cat Id 01 dfldng di qua day cua gdc 60°.
Tai mat cdt thfl 2, 3, ... 50 ta cd giao cua mat cat vdi be mat chi tiet la 02 dfldng di qua cac canh cua gdc 60°
A Anh Idt cat thil 20 B - Be mat chi tiet qua md td bdng phdn mem cua hdng KEYENCE Hinh 1. Anh thu dUdc tren kinh hien vi Keyence VHXIOO
U'ng dung chflong trinh viet bang ngdn ngfl lap trinh C#, ta se thu dflpc bien dang cua anh tai Idt cat 20 nhfl sau:
TAP CHI CO KHI VIET NAM V S 6 l 2 (Thang 12 nam 2011)
NGHIEN cufu - TRAO D 6 |
A Lav bien theo Kirsh B Lay bien ihco j^rewitt
C - Lay bien theo Sobel D Lay bien theo Difference
Hinh 2: Bien dang cua Idt cat thU20 khi dp dung cdc phUdngphdp lay hien neu tren
5. KET LUAN qua trong viec trich chpn cac dac trflng cua tflng lat cat anh cua chi tiet tai cdc dp cao z khdc Bang each tim hieu nhflng Idi md thuat nhau. Md ra flng dung cdc ky thuat dd bien ndy toan phdt hien bien cd the mac phdi ta cd the rut vdo md ta profile be mat chi tiet sau gia cdng ra phflong phap phat hien bien phu hpp nhat. tren mdy CNC (xay dflng bd dfl lieu cdc dfldng
ddng mflc). • Vdi viec phat hien bien nhfl the se rat hieu
Tai lieu tham khao:
1. Pham Viet Binh, Phat trien ky thuat dd bien, phdt hien bien vd flng dung, Luan dn Tien sy, (2007) 2. Pham Viet Binh, "Mot sd tinh chat cua phep todn hinh thai vd flng dung trong phat hien bien". Tap chi Tin hpc vd Dieu khien hpc. Tap 22, sd 2, 2006, tr 155-163.
3. Nguyen Thi Phflpng Mai, Luan dn Tien si ky thuat, Trfldng Dai hpc Bach khoa Hd Ndi, (2003) 4. David Whitehouse, Surfaces and their measurement, Hermes Penton Science, (2002)
TAP CHI CO KHI VIET NAM