MULTI-PASS EXPERT CONTROL-SYSTEM - A CONTROL SCHEDULING STRUCTURE FOR FLEXIBLE MANUFACTURING CELLS

Expert systems are currently being touted as a means to resolve manufacturing scheduling problems. Unfortunately, the expert systems developed to date are neither generic nor responsive enough to be used for on-line system control. A control structure is outlined which takes advantage of both expert system technology and discrete event simulation. The simulation is used as a prediction mechanism to evaluate several possible control alternatives provided by the expert system. A performance measure is obtained from the simulation for each of the suggested alternatives. A control effector is employed to affect the physical control of the cell based on the measure. This performance measure is worth a great deal of domain-specific knowledge that otherwise would have to be included in the expert system knowledge base. The integration of the expert control system, the simulation, and the control effectors form a system called a multipass expert control system (MPECS). MPECS is designed for the control and scheduling of flexible manufacturing cells.