Design and control of automated guided vehicle systems

Exact polynomial algorithms to solve the idle AGV positioning problems in both unidirectional and bidirectional single loop systems have been developed for two different purposes: minimizing the maximum response time and minimizing the mean weighted response time. The proposed dynamic programming (DP) algorithms, partition the set of pick-up stations into subsets so that all stations in a subset are served by a single vehicle. The DP algorithms have been streamlined by using certain optimality properties. Computational results show that the proposed algorithms can solve large-scale problems in reasonable CPU time.; The Tandem Loop with Multiple Vehicles (TLMV) configuration is considered as a new and significant layout alternative. The TLMV configuration is especially useful for a large scale manufacturing environment. In order to provide formal design procedures for the TLMV configuration, heuristic algorithms are developed using clustering techniques. For the TLMV layout, exact polynomial algorithms to determine the optimal idle vehicle dwell point locations are proposed.; In order to analyze deadlock, Colored Petri Nets (CPNs) are employed to model manufacturing systems. Circuits in the CPN model identify circular waits among part transitions, which cause deadlocks. In addition, the impending deadlocks are analyzed, and the intersection place is introduced to explain impending deadlocks. Based on the CPN model, deadlock prevention and detection algorithms have been developed. Systems that have a limited number of buffer spaces and allow routing flexibility are also studied. When routing flexibility is allowed, the system is not deadlocked until all places that may be reached are occupied with jobs in circular waits. A closed connected set is defined by these places. An algorithm to identify closed connected sets in a CPN model is developed. The proposed algorithms prevent deadlocks in assembly and disassembly systems as well.; The simulation language ARENA is used to build a model that describes the operations of AGV systems. The simulation study compares the performance of the proposed TLMV configuration against the performances of other guide path systems. In addition, the effect of idle vehicle management policies and the performance of deadlock prevention control schemes are investigated.