Flexibility Support for Human-Intensive Assembly Systems

Flexibility is a major driver of the manufacturing mass-customization trend enabling companies to produce highly customizable goods, in small lot sizes, at the costs of mass production. Flexibility is required at various phases of production (including the planning and assembly phases). It enables assembly systems to quickly and efficiently respond to external disturbances such as market volatility and supply chain disruptions and internal disruptions such as assembly errors, workforce availability, etc. Ensuring flexibility in assembly systems is nonetheless challenging. Throughout this thesis, we particularly examined the challenges associated with implementing flexibility during the planning and assembly phases. On the one hand, flexibility during the planning phase requires rapid balancing of new products and re-balancing of existing ones. However, the previously proposed automatic balancing solutions are not always applicable in real-world industrial settings. This is primarily due to the lack of required input data, namely the precedence graph. In reality, assembly lines are often balanced manually and in multiple iterations, requiring a significant amount of time and effort. During the assembly phase, on the other hand, flexibility is required to allow workers to respond to unforeseen situations on the shopfloor. While ensuring the necessary flexibility for the assembly process, humans also introduce uncertainties. It is therefore critical to monitor the ongoing process and be able to detect deviations from expected behavior. This timely detection is necessary so that mitigation actions can be promptly planned to avoid major disruptions or irreversible quality defects. The purpose of this thesis is to support the flexibility of assembly systems during the planning and assembly phases. It especially focuses on the challenges real-world assembly systems face in implementing the much-needed flexibility. More specifically, we support the prompt balancing of new products while addressing the lack of vital ...