Sustainable Design and Control of Automated Material Handling Systems

Doctoral thesis, 2012

An automated material handling system is a collection of electro mechanical components, electronics, and computer-based devices that act together to maintain flow of parts and materials in a modern production environment. Material flow is a significant factor in the design of manufacturing plants. Failure to fully integrate handling devices in a manufacturing plant results in a huge waste of production time, space, resources, and energy. To prevent this failure, this thesis work establishes a framework to design and control an automated material handling system according to the sustainable production philosophy. Conceptual and detailed design activities are established in the framework to fulfill the philosophy objectives. In the conceptual design phase, an evaluation method and a synthesis method are combined to maximize precision and minimize time of the design procedure. For the evaluation method, a universal model to concurrently evaluate a wide range of possible design architectures and control strategies for an automated material handling system is introduced and developed in Colored Petri Net (CPN) tool. A great number of configurable parameters in this model provides a precise insight into transition and stationary analysis of an automated material handling mechanism. However, the precise analysis is often paid by massive evaluation time. To reduce the time, furthermore, mixed integer linear programming models are employed to synthesize initial values of the configurable parameters according to lean, green, and agile issues. In the detailed design phase, a sustainable design and control of pallet systems is the main concern in the thesis work. Given a complex pallet system, a procedure to decompose the system into some simple loops (zones) for the design analysis is introduced. Then, a generic design framework for a one-loop pallet system (zone) based on optimization models is established. The constraints in the models characterize conditions on smooth running, energy reduction, dynamic and cyclic behavior, parts scheduling, conservation of the number of pallets, and buffer capacities for a one-loop pallet system. Moreover, the objective functions realize sustainable design issues such as minimum energy consumption, minimal chain tension force, and minimum number of pallets and buffer sizes. Two examples are presented to show applications of the developed framework for sustainable design and control of pallet systems.