Deadlock-free multi-attribute dispatching method for AGV systems

摘要

This paper aims at developing a flexible, efficient, and deadlock-free dispatching method for automated guided vehicle systems. For this purpose, a deadlock-free multi-attribute dispatching method with dynamically adjustable weights (AWMA) is proposed. Traveling distance, input, and output buffer statuses are selected as dispatching attributes according to the efficiency and deadlock avoidance requirement. The weight for each attribute is dynamically adjusted according to the processing load and transportation load of the system. To ensure the system to be deadlock-free, a deadlock avoidance policy based on remaining capacity concept is introduced. It works by temporarily forbidding critical tasks according to the system state, which will otherwise cause system deadlock. The AWMA method is formed by integrating the deadlock avoidance policy into the multi-attribute dispatching procedure. To validate the effectiveness of the proposed method, several simulation experiments were carried out to compare three commonly used dispatching methods with the proposed one under different system settings. The simulation results indicate that the deadlock avoidance policy can guarantee the system to be deadlock-free and that the proposed method is efficient.