Intelligent scheduling based on start time adjustment for advanced sequential control systems

Abstract

Syst em s D evel opm ent Laborat ory, H i t achi Lt d. 1099 O zenj i , Asao, Kawasaki , 215-0013, Japan E-m ai l : ai zono@ sdl . hi t achi . co. j p **) D epart m ent of Inf orm at i cs and M at hem at i cal Sci ence, G raduat e School of Engi neeri ng Sci ence, O saka U ni versi t y 1-3 M achi kaneyam a-cho, Toyonaka, O saka 560-8531, Japan E-m ai l : ki kuno@ i cs. es. osaka-u. ac. j p A bstract H i gh product i vi t y i s required for i ndust rial system s t hat are t o produce l arge am ount s of l ow-pri ce product s. M ost i ndust rial system s are sequent i al l y cont roll ed because m at eri al s and part s are processed and const ruct ed step by step. A new m et hod of sequent i al cont rol i s needed t o i ncrease product i vi t y, and a new t echni que t o schedul e t he start t i m e of each process i s al so needed because of f requent adj ust m ent of product i on l i nes and t hei r equi pm ent . Int el l i gent devi ces such as i nt el l i gent sensors and act uat ors used in t he l at est i ndust rial system s have em bedded hi gh-perf orm ance processors and cont ai n soft ware m odul es. These devi ces cooperat e and cont rol processi ng robot s and product i on l i nes. Advanced sequent i al cont rol i s proposed f or sequent i al cont rol system s consi sti ng of di st ri but ed sof t ware m odul es. Processi ng t i m e can be m i ni m i zed and product i vi t y i ncreased by i nt el l i gent schedul i ng f or advanced sequent i al cont rol, and t hi s paper describes a new m et hod f or adj ust i ng t he st art i ng t i m es of product i on processes aut om at i cal l y. Thi s m ethod short ens t he t i m e m argi n and decreases t he t ot al processi ng t i m e. Thi s paper al so describes a Processi ng Fl ow D i agram t hat m akes i t easy t o adj ust t he st art i ng t i m e of each process. The ef f ect i veness of thi s int el l i gent schedul i ng and st art -t i m eadj ust m ent has been dem onst rated by usi ng t hem t o opt i m i ze t he operat i on of a system f or t est i ng di sk pl at es.