On the assessment of manufacturing systems complexity

• Κύριος συγγραφέας: Ευθυμίου, Κωνσταντίνος
• Άλλοι συγγραφείς: Χρυσολούρης, Γεώργιος
• Μορφή: Thesis
• Γλώσσα: English
• Έκδοση: 2013
• Θέματα: Manufacturing systems; Complexity; Flexibility; Shannon entropy; Kolmogorov complexity; Automotive industry; Συστήματα παραγωγής; Πολυπλοκότητα; Ευελιξία; Εντροπία Shannon; Πολυπλοκότητα Kolmogorov; Αυτοκινητοβιομηχανία; 670.11

Objective of the present study is the development of methods for the assessment of manufacturing systems complexity and the investigation of flexibility and complexity relationship. Towards this target, a complete approach based on information theory permitting the analytical, quantitative and systematic modeling and quantification of both static and dynamic manufacturing complexity is proposed. Static complexity concerns the structure of the manufacturing systems, namely the products, the processes, the resources that constitute the systems as well as their interconnections. Static complexity is treated as the information that is required for the description of a manufacturing system. Multi domain matrices modeling the relationships between products, processes and resources are formalized as networks following the notions of graph theory. The information content of each matrix is assessed employing Shannon entropy measure and their aggregation yields the static complexity. Dynamic complexity is related to the uncertainty in the behaviour of a manufacturing system and in the present study is associated with the unpredictability of the performance indicators timeseries. The unpredictability of the performance indicators timeseries, which are provided by computer simulation, is captured employing the Lempel Ziv algorithm that calculates the Kolmogorov complexity. The dynamic complexity is either the unpredictability of a specific timeseries or the weighted mean of a series of performance indicators timeseries produced under different product demand scenarios. The relationship between flexibility and complexity is investigated for a group of 19 different configurations of a manufacturing system. In particular, operation flexibility that refers to the system’s ability to produce a set of products through different machines, materials, operations and sequences of operations and total complexity, and both static and dynamic are examined employing a utility function. As a case study, two assembly lines producing three car floor model types at three different product mixes are investigated. The dynamic complexity of each assembly line is assessed and the relationship between product mix and dynamic complexity is studied. The evaluation of the case study revealed the efficiency of the suggested approach validated its applicability to industrial environments.