A Conjunctive-disjunctive Graph Modeling Approach for Job-Shop Scheduling Problem with Changing Modes

International audienceReconfigurable Manufacturing Systems (RMS) have been defined in (Mehrabi et al., 2000) as an effective approach to deal with unpredictable and high-frequency market changes that are facing industries. To cope with such changes, the production systems must be adaptive and able to evolve in order to consider 1) changes in parts of existing products; 2) fluctuations in demands; 3) evolution in legal regulations and 4) evolution in process technology. Meanwhile, the scheduled operations remain partially manual like material handling, carrying and processing jobs as stressed by (Napolitano, 2012). The assignment of operators to operations must include personal skills, training and experience in order to match the competences and/or functionalities required by the operations to be performed (Ferjani et al., 2017; Grosse et al., 2015). In RMS, the sequential execution of operations may depends on the job operation sequence that can refer to Flow-shop, Job-shop, etc. Including flexibility for processing operations remains possible at each step of the job-sequence. Meanwhile, reconfigurability is the capacity of a set of machines to be reconfigured in a period of time, which can be seen as setup times. Machine activation delay may include cleaning the working zone, loading, positioning and unloading the parts (jobs) and can imply costs coming from energy expenditures, equipment maintenance and labor as stressed by (Borgia et al., 2013). Hence, in RMS a solution is composed by a set of configurations applied sequentially and thus a sequence-dependent processing time of operations and sequence dependent setup times have to be considered in such a production system. If sequence depend setup times are features of several research projects in the scheduling community as stressed in (Sharma and Jain, 2016; Shen et al., 2018), these works generally consider setup times at the operation level, whereas several modifications of the system may occur in RMS requiring several resources to be inactive during reconfigurations..