Message exchange method for decentralized scheduling

Scheduling is one of the important problems in assembly planning and task planning. A message exchange method is proposed in order to make schedules decided by individual machines in a decentralized manufacturing system. The message exchange method which is called the recursive propagation method, is related to procedures of information processing exchanged among machines, and makes them identify the status of the whole system when each machine changes the sequence of task operations. In the paper, a procedure of information processing is proposed and explained in detail. Furthermore, an improved algorithm is proposed in order to reduce the number of the information exchanges required among machines. The proposed method is implemented onto several computers which can communicate by using UDP/IP on a network. The feasibility of the methodology proposed is also verified by computational simulations