Real-Time Control for Job-Shop Scheduling

Since job shop production procedure diverts always from original scheduling plan, it is essential to renew the plan for delivery time. An automatic control theory is presented, whose principles include sampling, identification and calculation. The information of the deviation from original scheduling plan is sampled as production state, and original scheduling order is resumed to insure their delivery time; All jobs are prioritized and arranged. The important jobs are allocated firstly by delivery time; Other jobs are arranged for short makespan subsequently, thus the related state is renewed, whereby a new scheduling plan is deduced. The algorithm translates routing matrix into equipment sequence matrix. Sequence functions are from delivery time or residual process time. According to sequence function and equipment sequence matrix, the job order is formulated for its process on machines. Recurrence formula of job states is studied out. A simulation example is shown.