CP APPROACH TO DESIGN OF STEADY-STATE FLOW OF REPETITIVE MANUFACTURING PROCESSES IN SME

Concurrent execution of work orders in the small and medium size enterprises (SME) imposes a necessity to consider many control problems concerning systems of repetitive concurrent manufacturing processes using common resources in mutual exclusion. In many cases a production system with a given structure of the processes resource requests can be seen as composed of subsystems with n cyclic processes sharing one resource. For given sets of possible values of the processes operation execution times a problem of finding schedules guaranteeing that no process waits for access to the common resources is considered. In particular for the assigned times of the operations execution a subproblem of finding all possible starting times of work orders execution for which waiting-free schedules exist has been formulated as a constraint programming (CP) problem. The starting times derived can be used as an alternative starting times of work orders execution in case of their possible delays. A state space of the problem’s solutions has been reduced using constraints based on the necessary and sufficient conditions for existence of a waiting-free n-process steady-state schedule. An illustrative example of Mozart-based software application to the solution of constraint logic programming problem considered has been presented