Variance-based approximations of transaction waiting times in autonomous vehicle storage and retrieval systems

TLDR: Simulation-based validation studies indicate that this strategy can reduce the magnitude of errors in estimated transaction waiting times by approximately 80% relative to static approximations.

Abstract: Approximation strategies for transaction waiting times are proposed for use in Autonomous Vehicle Storage and Retrieval Systems (AVS/RSs) with non-Poisson arrival rates and non-exponential service times. The proposed modelling tools dynamically adjust approximations based on the variance of the transaction inter-arrival times observed in a system. Simulation-based validation studies indicate that this strategy can reduce the magnitude of errors in estimated transaction waiting times by approximately 80% relative to static approximations. The design conceptualisation applications of the proposed technique are demonstrated over a series of realistically sized demonstration problems. (Received 8 April 2008; Revised 20 July 2008; Accepted 2 August 2008)