ABSTRACT
Figure 6 .1 : Illustration for Example 1. (a) A flexible assembly cell and (b) a diagram of the material flow.
Example 1 Figure 6.1(a) presents the structure of an example assembly cell that consists of four workstations, mi, m2 , m3 , m4 , with buffers b\, Ò2, b?>, ^4 , respec tively, two individual buffers 6 5 and b6 accessible for the manipulators of both m3 and m4 , and two handling robots r\ and Г2 . The robots transport materials from/to the system input/output and between buffers. Pallets with base components are han dled by robot r\ and placed in buffers 6 2 > £3 , or Ы, while trays with subassem blies and unpalletized components are handled by robot Г2 and placed in buffers bu t>5 or be-The flow of material objects in the cell is depicted in Figure 6.1(b). The graph consists of two disjoint subgraphs corresponding to two compound pro cesses K\ and K2 . The vertices represent technological and transport operations, and
the edges represent material units at a particular stage of their route. The symbols placed next to a vertex and its input and output arcs denote the resources required for the corresponding operation which are: the machine, and the buffers to store the material units (pallets, trays, and unpalletized components) before and after the operation. Operations 1-11 and 23-29 involve base components of П\ and π2 , respec tively. 1,3,5,7,9,11,23,25,27,29,31 are transports of base components, operations 12,14,15 correspond to the transport of trays with subassemblies, and operations 18,20,22 correspond to the transport of unpalletized components. Vertex 13 repre sents mounting of a subassembly ; vertices 6 , 1 0 represent mounting of subassemblies carried on pallets onto base components; and operations 24,28 represent mounting of unpalletized components onto base components. Operation 21 is performed ex clusively on unpalletized components. In transport operation 18 two components are handled at a time, one of which is mounted onto a base component in workstation m3 , while the other is further transported to mi.
