Comparison of heuristics for reschekuling in permutation flowshops

Rescheduling is one of the main consequences of the variability in the shop floor, as a number of unforeseeable disruptions make impossible to follow the original schedule (Wu et al (1993)). Typical disruptions are the arrival of new orders, order cancellations, rush orders, etc (Hall and Potts (2004)). In the case of the arrival of new jobs at the time that the current schedule is being executed, there are two broad options for the scheduler: a) considering the jobs in the system as ‘frozen’ (i.e. the schedule of the previous jobs is maintained) or b) allowing the modification of the schedule of the jobs in the system and rescheduling them together with the new jobs. The first approach implies a machine availability constraint problem, denoted MACP, studied by Perez Gonzalez and Framinan (2009). The second approach is addressed in this work.