"thu vien sach co khi" – thiet ke mach dieu khien he thong khi nen va thuy luc

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THU VIEN SACH CO KHI – THOA SUC KHAM PHA http://facebook.com/thuviensachcokhi/: Thư Viện của những trải nghiệm và cơ hội kiếm thêm thu nhập Rất mong được sự đóng góp và giúp đỡ của các bạn để trang ngày một lớn mạnh và phục vụ cộng đồng một cách tốt hơn đem lại những giá trị khác cho cuộc sống Email : thuviencokhi@gmail.com

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  • 1. IEU KHIEN KH NEN & THUY LC Chng 7 Thiet ke mach ieu khien PHAN III PHAN TCH VA THIET KE CHNG 7 THIET KE MACH IEU KHIEN HE THONG KH NEN THUY LC Bieu dien chc nang cua qua trnh ieu khien Bieu o trang thai S o chc nang Lu o tien trnh Cac phng phap ieu khien ieu khien tuy chon ieu khien theo hanh trnh ieu khien theo thi gian ieu khien phoi hp Thiet ke mach ieu khien ien thuy kh Nguyen tac thiet ke Phan tch va thiet ke Thiet ke mach ieu khien bang lap trnh Cong cu thiet ke Viet chng trnh ieu khien 94
  • 2. Chng 7 Thiet ke mach ieu khien IEU KHIEN KH NEN & THUY LC Trong ky thuat ieu khien, cac hoat ong cua cac c cau trong he thong ieu khien t ong eu xuat phat t cac phng trnh chuyen ong c xay dng tren nguyen ly lam viec cua he thong. Cac phng trnh nay la ham tch hp nhng gia tr cua tn hieu vao va tn hieu ra va c viet di dang cac bien so cua ai so Bool. Qua trnh nh ngha tn hieu vao ra ay u, tuan thu nguyen ly hoat ong cua he thong e xay dng c cac ham toi u, tc giam thieu c toi a cac phan t logic trong thiet ke la mot nhiem vu quan trong trong ky thuat ieu khien. Tuy theo mc o n gian hay phc tap cua hoat ong he thong ta co the co t hay nhieu phng trnh ieu khien. V du: C cau mot au khoan t ong thuy lc mo ta hnh 7.1, vi yeu cau ky thuat nh sau: a chi tiet can khoan vao v tr can khoan, khi o ta an nut Start PB, au khoan tnh tien en va khoan chi tiet. at en chieu sau can thiet (S2) au khoan t ong quay ve. Trong qua trnh khoan neu xay ra s co ta an nut Stop PB au khoan t ong lui ve. StartPB StopPB au dao khoan S1 1 2 Chi tiet khoan S2 Than ban may Hnh 7.1 C cau khoan Hnh 7.2 Mach thuy lc c cau khoan Qua phan tch nguyen ly lam viec cua c cau khoan ta thiet ke c mach ong lc nh hnh 7.2. Phng trnh ieu khien c viet nh sau: K = {[(StartPB S1) K] S2} StopPB Phng trnh tai: 1Y = K Trong o: - ham K c xem la cuon day cua relay mach ien. - 1Y la cuon day cua van ien t thuy lc. Da vao phng trnh ieu khien va phng trnh tai, mach ien ieu khien c thiet ke nh hnh 7.3 va mach ieu khien bang thuy lc hnh 7.4. 95
  • 3. Chng 7 Thiet ke mach ieu khien IEU KHIEN KH NEN & THUY LC Mach ieu khien Hnh 7.3 Mach ien ieu khien Hnh 7.4 - Mach ieu khien bang thuy lc 7.1. LY THUYET AI SO BOOLE 7.1.1. cac phep bien oi ham mot bien PHNG TRNH MACH IEN MACH LOGIC 0 A A A0=0 & 0 A1=A A 1 1 A & A AA=A A A A A & A AA=0 A A A A & 0 A=A A0=0 A1=A A A 1 AA=A A AA=1 A A 1 A 1 A 0 1 A A 1 1 1 A A 1 A A A 1 1 96
  • 4. Chng 7 Thiet ke mach ieu khien IEU KHIEN KH NEN & THUY LC 7.1.2. Cac luat c ban cua ai so Boole 7.1.2.1. Luat hoan v PHNG TRNH MACH IEN MACH LOGIC A B A B & B A B A & A B 1 B A 1 AB=BA A B B A AB=BA 7.1.2.2. Luat ket hp PHNG TRNH MACH IEN MACH LOGIC A C A B C A B C A B C & A B (A B) C = A(B C) B B 1 C A C A B C A B C 1 (A B) C = A (B C) & & & 1 1 7.1.2.3. Luat phan phoi PHNG TRNH MACH IEN B C A (AB)(AC) = A(BC) A A B C A A B (AB)(AC) = A (BC) A B C C MACH LOGIC & A B 1 C & A B C A 1 1 B C 1 A B C & & & 1 97
  • 5. Chng 7 Thiet ke mach ieu khien IEU KHIEN KH NEN & THUY LC 7.1.2.3. Luat hap thu PHNG TRNH MACH IEN A A A A (A B) = A MACH LOGIC B B A A A (A B) = A 1 A A B AA 1 & & 1 B A A 1 7.1.2.4. Luat bu PHNG TRNH MACH IEN A B A A (A B) = A B A MACH LOGIC 1 B A A B B A (A B) = A B B A 1 A A A 1 & 1 B 1 A B B & & 7.1.2.5. Luat De Morgan PHNG TRNH MACH IEN MACH LOGIC A & B AB =A B A 1 B 1 A A B =A B 1 1 B A 1 B 1 & 98
  • 6. Chng 7 Thiet ke mach ieu khien IEU KHIEN KH NEN & THUY LC V du: n gian phng trnh sau: y = ( A B D) ( A B D) Giai: Phng trnh tren co chung tham so A B . Theo luat phan phoi ta viet lai phng trnh tren nh sau: y = ( A B) ( D D) Theo phep bien oi ham 1 bien th: ( D D) = 1 Do o: y = ( A B) 1 = ( A B) V du: n gian phng trnh sau: y = ( A B) ( A B) Giai: Theo luat phan phoi ta viet lai phng trnh tren nh sau: y = ( A A) ( A B) ( B A) ( B B) Theo phep bien oi ham 1 bien th: A A = 0 va B B = B Suy ra: y = 0 ( A B) ( B A) B y = ( A B) ( B A) B V du: n gian phng trnh sau: y = ( A C ) ( B D) Giai: Theo luat De Morgan ta co the viet lai nh sau: y = ( A C ) ( B D) Cung theo luat De Morgan ta viet lai: y = ( A C) (B D ) Theo phep bien oi ham 1 bien th: A = A va D = D Do o: y = ( A C) (B D ) 99
  • 7. IEU KHIEN KH NEN & THUY LC Chng 7 Thiet ke mach ieu khien II. PHAN LOAI PHNG PHAP IEU KHIEN 1. ieu khien tuy chon ieu khien tuy thuoc la ieu khien thng cac tac ong c thc hien bang tay hay bang chan. Trong ieu khien kh nen thuy lc tuy thuoc tn hieu au vao la cac van tac ong bang tay, chung kch hoat cac pt tong dch chuyen ve pha trc hoac tr ve v tr ban au theo mong muon. Hnh 7.5 mo ta mach dap n gian ieu khien tuy chon. Gom mot van 4/3 co nh 2.6, mot phan t OR va 3 van tac ong tn hieu bang tay. Tat ca nhng ieu khien tuy thuoc oi hoi van hanh cua con ngi mi tr nen hieu lc. ieu khien tuy thuoc thch Hnh 7.5 ieu khien hp bat c ni au ma ta khong quan tam tuy thuoc en chu trnh lam viec t ong cua he thong. Noi mot cach khac, ay la mot loai ieu khien phu hp oi vi nhng he thong hoat ong n gian, th du nh kep chat, nang chuyen, nh vong thi no cung la coi nguon cua he thong phc tap na o la chi tiet can thiet cho s khi ong hay ngng khan cap tac ong trong cac may t ong. 2. ieu khien theo hanh trnh Trong mot he thong ieu khien theo hanh trnh, hoat ong cua cac phan t a tn hieu khi ong cac c cau chuyeu hng hay van hanh cac vong lap ieu khien khac c thc hien bi chnh cac phan t chap hanh. Cac tn hieu hanh trnh c kch trc tiep t can pit tong cuoi cua moi hanh trnh. Tuy nhien e thc hien nhng nhiem vu hoac nhng yeu cau nao o, ta co bo tr cac tn hieu hanh trnh nhng v tr bat ky tren khoang chay cua pt tong. Hnh 7.6 mo ta mot mach lam viec c lap i lap lai. Ngay khi nguon kh cung cap c m bi van 0.1, pt tong c khi ong qua lai trong xy lanh cho ti khi nguon kh cung cap c ong Hnh 7.6 ieu khien theo hanh trnh lai. Van tac ong con lan 1.1 va 1.2 c bo tr nh cac hanh trnh e a tn hieu ti van nh trang thai 4/2 1.3 khi can pit tong cham vao con lan. 100
  • 8. IEU KHIEN KH NEN & THUY LC Chng 7 Thiet ke mach ieu khien 3. ieu khien theo thi gian ieu khien theo thi gian la trang thai ieu khien cua he thong tac ong ch phu thuoc vao ai lng thi gian cua cac phan t nh thi. Cac phan t nh thi co the la kh nen, dau ep hoac ien. Hnh 7.7 mo ta he thong ep ui hi ket non. Khi nhan nut an S1 van ao chieu 1Y oi v tr, pittong 1A i len e ep ket non, ong thi dong ien vao phan t relay thi gian T1. Sau thi gian t th pittong se i xuong tr ve v tr ban au. Hnh 7.8 la c cau ieu khien dch chuyen pittong kh nen e ay cac Hnh 7.7 ieu khien theo thi gian san pham theo nguyen ly thi gian. Vi cac phan t thi gian s dung nguon nang lng lu chat th ch hoat ong hai v tr cuoi cua xylanh kh nen. Thi gian tr hoan phu thuoc vao o hieu chnh cua van tiet lu. 4. ieu khien phoi hp ieu khien phoi hp la ieu khien phoi cac ieu khien tren. Hnh 7.9 la mo ta Hnh 7.8 ieu khien theo thi gian bang lu chat kh nen mach ieu khien cua c cau ep phoi hp 3 thanh phan ieu khien: tuy chon (2.3), hanh trnh (2.2) va thi gian (2.5). Bnh thng khi cap nguon nang lng th phan t 2.5 xac lap thi gian va sau thi gian nay th co dong nang lng tao ra nhng no i qua ca xa cua 2.3 khong u ap e kch van 2.4. Ngc lai neu tac ong 2.3 ma 2.5 cha xac lap th dong nang lng c tao ra cung khong kch cho van 2.4 hoat ong. Tn hieu kch van 2.4 dch chuyen vi ieu kien ong thi nut nhan 2.3 c tac ong va sau thi gian xac lap cua phan t 2.5. Khi pittong Hnh 7.9 ieu khien ep phoi hp 101
  • 9. Chng 7 Thiet ke mach ieu khien IEU KHIEN KH NEN & THUY LC ep i ra va cham vao cong tac hanh trnh 1.2 th van 2.4 b kch ngc lai va pittong lai tr ve v tr ban au. 5. ieu khien theo chng trnh cng Cac ieu khien may moc hoan toan t ong c phan theo y muon va c ch nh theo cac ieu khien chng trnh hoac cac ieu khien lien tuc. Ca hai he thong co nhng ch li va nhng bat li. Vi ieu khien chng trnh, cac tac ong c thi hanh theo s thoa thuan vi mot chng trnh nh ngha trc. Thong thng bo chng trnh bao gom mot cai truc c van hanh bang ien lap vi mot so cam (chi tiet cam c kh) p Truc cam Pt tong cat Pt tong kep p Pt tong tai phoi Thep cay Banh cam p Pt tong dap p Con lan Pt tong ay thep a cat Phoi thep cuon p ong c ieu khien ong bo ieu khien mot so van tng ng. Chng trnh c bien dch bi cac cam c lap at chnh xac va toc o quay cua truc cam. Hnh khai trien 7.10 mo ta mot ieu khien theo chng trnh cng ieu khien may nong au cat ong nha theo kch thc. Toc o cua ong c