Travel-time models considering the operating characteristics of the storage and retrieval machine

Abstract

Travel-time models considering the operating characteristics of the storage and retrieval machine HARK HWANGt and SEONG BEAK LEEt Existing travel-time models of automated storage/retrieval systems (AS/RS) assume the average uniform velocity, ignoring the operating characteristics of storage/retrieval (S/R) machine such as the acceleration/deceleration rate and the maximum velocity. Consequently, the optimal design and schedule based on the existing models is far from optimal from the practical point of view. This paper presents continuous analytical models of travel time which integrate the operating characteristics ofS/R machine. Using a randomized assignment policy,travel times are determined for both single and dual command cycles. The models developed are examined through discrete evaluation procedures.

A survey of literature on automated storage and retrieval systems

“…Hwang and Lee (1990) incorporate both the maximum velocity of a crane and the time required to reach the peak velocity or to come to a halt. Chang et al (1995) extend the work of Bozer and White (1984) by including acceleration and deceleration rates instead of assuming constant speed.…”

Simulation-Based Performance Analysis of Automated Single-Tray Vertical Lift Module

“…Models are based on randomized storage and retrieval request, assuming that the S/R machine travels all the time with constant velocity. Hwang and Lee [10] presented travel time models considering the real operating characteristics of the S/R machine in non-SIT racks. Sari et al [11] presented closed-form travel-time expressions for flow-rack AS/RS.…”

Supply Chain Management Based on Modeling & Simulation: State of the Art and Application Examples in Inventory and Warehouse Management

“…• aisle based models which focus on a single storage system and evaluate travel and service time; examples of aisle based models can be found in Hwang and Lee (1990), Chang et al (1995), Chang and Wen (1997), Lee (1997), Hwang et al (2004), Meller and Klote (2004), Roodbergen and Vis (2006); • integrated models which address (in addition to travel/service times) either multiple storage systems and criteria; examples of integrated models can be found in Malmborg (1996), Malmborg and Al-Tassan (2000). Finally a number of studies propose advanced tools (also based on simulation) to address warehouse performance evaluation and enhancement problem.…”