A GENERALIZED CONTROL MODEL FOR MAN-MACHINE PRODUCTION SYSTEMS WITH DISTURBANCES

A control model for a two-level man-machine production system is consi dered. The system comprises a section and several production units. Wi thin the planning horizon the section is faced with manufacturing seve ral different products with planned target amounts. Each unit can manu facture all kinds of products. In the course of manufacturing, each un it utilizes different types of non-consumable resources which may be r eallocated among the units. Each production unit can manufacture a pro duct at several possible speeds which correspond to one and the same r esource capacities. Those speeds depend only on the degree of intensit y of manufacturing and are subject to random disturbances. To carry ou t the process of manufacturing, the products have to be rescheduled am ong the units. This means that for each unit and for each product assi gned to that unit the corresponding planned amount and the planning ho rizon have to be determined. Controlling the system is carried out at two levels: the section level and the unit level. At the unit level al l production units are controlled separately. For each unit and for ea ch product manufactured by that unit decision-making centers on determ ining: (i) control points to observe the product's output; (ii) the sp eeds to manufacture the product. If at a routine control point it is a nticipated that a unit is unable to meet its deadline on time, emergen cy is called. The section level is then faced with the problem of both resource and target amount reallocation among the units. New resource capacities and target amounts for each product and each production un it are decision variables to be determined. The objective is to maximi ze the probability of the slowest unit to accomplish the planned amoun ts of its products by the due date. The problem is too difficult to ob tain a precise or even an approximate solution. Heuristic algorithms a re outlined on both levels. The model's performance is verified via ex tensive simulation. (C) 1997 Elsevier Science Ltd.