Constraint-Based Reactive Rescheduling in a Stochastic Environment

The problem of scheduling manufacturing systems where the capacity of a production resource is subject to stochastic change, is the subject of this paper. Resources which are dependent upon labour intensive processes provide typical examples. In the United Kingdom the manufacture of clothing garments is still dominated by the progressive bundle system. Garments are produced on a continuous-ow production line in which garment pieces are passed in succession through a network of workstations where skilled manual workers complete operations on garments using sewing machines. These production systems are subject to numerous perturbations caused by operator absenteeism and machine breakdown necessitating the need for reactive rescheduling to maintain line balance. In the approach described here, line balance is maintained via periodic schedule repair, based upon reassignment heuristics, supported by partial order backtracking.