A multi-objective GA to demand-side management in an automated warehouse

The simultaneous operation of the automated storage and retrieval machines (ASRs) in an automated warehouse can increase the likelihood that high power demand peaks turn unstable the electric system. Furthermore, high power peaks mean the need for more electrical power contracted, which in turns leads to more fixed operation cost and inefficient use of the electrical installations. In this context, we present a multi-objective genetic algorithm approach (MOGA) to implement demand-side management (DSM) in an automated warehouse. It works minimizing the total energy demand, but without increasing substantially the time for the operation. Simulations show the performances of the new approach.Peer ReviewedPostprint (published version

Permanently installed rope monitoring in conveyor systems

A permanently installed rope monitoring system can help to avoid unplanned downtimes and increase the safety level. The aim here is to set up a rope monitoring system that helps to monitor the hoisting rope as a critical component and to minimise downtimes in the context of "predictive maintenance". The already applied magnetic inductive rope testing can be used as a testing method. The paper deals with the topic of integrating such a permanently installed testing device, its use and evaluation strategies, and it identifies possibilities for new business areas for rope testing

Simulation based performance analysis of an end-of-Aisle automated storage and retrieval system

This paper presents and discusses simulation of an End-of-Aisle automated storage and retrieval system, using FLEXSIM 6. The objective of the simulation model is to analyze and compare results of different control policies and physical designs. The performance measures considered for the evaluation of each control policy and layout combination are the total travel time of the crane and the number of storage and retrieval operations performed. The experiments set up and the corresponding results are discussed

A Roadmap towards an Automated Warehouse Digital Twin: current implementations and future developments

Automation and digitization increase the effectiveness and efficiency of logistics processes. In warehousing, Automated Storage and Retrieval Systems (AS/RS) are largely adopted due to their considerable advantages over traditional warehousing, namely high space utilization, shorter cycle times and improved inventory control. To further enhance such advantages, warehouse operations can be digitized via a Digital Twin (DT) which retrieves data from the real-world industrial process, mimics its behaviour and feeds specific inputs back to the real-world process, after elaboration from a simulation-based digital model. This work presents a DT proposal for a real-world AS/RS system, highlighting its current implementations together with its future developments

Distributed parameter modeling of single-mast stacker crane structures

This paper presents distributed parameter dynamical modeling capabilities of single-mast stacker crane structures. In the frame structure of stacker cranes due to external excitation or inertial forces undesirable structural vibrations may arise. These vibrations reduce the stability and positioning accuracy of stacker crane and causes increasing cycle time of storage/retrieval operation. Thus it is necessary to investigate of these vibrations. In this paper the dynamical behavior of single-mast stacker cranes is approximated by means of distributed parameter models. The first model is a cantilever beam model with uniform material and cross-sectional properties. This model is used to demonstrate fundamental properties of Euler-Bernoulli beam models. The second model is cantilever beam model with variable cross-sectional properties and lumped masses. The eigenfrequencies and mode shapes of this mast-model are determined by means transfer matrix method. In the third model the whole structure of single-mast stacker crane is modeled

Application of Theory of Constraints (ToC) in Managing Project Information Constraints

The scope of this doctoral project is the non-traditional application of Drum-Buffer-Rope (DBR) from the area of Theory of Constraints (ToC) in mitigating disruption in distribution facilities during phased upgrades caused by information constraint. The relevance of this project is that industrial equipment upgrades pose a significant risk of disrupting the operation of automated distribution facilities. It is partly due to a very high expected availability rate, as well as tight coupling with other upstream and downstream elements of the larger supply chain network. As a consequence of disruption in this scenario, losses incurred not only within the facility being upgraded but also to the entire supply chain, as well. This project will particularly examine the potential non-traditional application of DBR. It is to mitigate risk brought by unavailable timely information during equipment upgrade by treating the information-time issue as a constraint that can then be elevated among various stakeholders and into the equipment upgrade schedule. This project contributes to the advancement of engineering management and project management practice in obtaining the appropriate information and data to minimize disruption posed by information-time constraint

Multiple-grooved Magnetic Traction Sheaves

This paper discusses a new and innovative form of traction sheaves, which can be used in many hoisting applications that are driven with wire ropes in material handling systems. By use of high performance permanent magnets, integrated in the periphery of traction sheaves, a significant increase of driving capacity is achieved. In this special case it concerns high energy magnets consisting of rare earth materials known as NdFeB magnets. These magnets provide a 20 times higher force than conventional magnets. The results of the research show that the driving capacity of traction sheaves with a round groove design can be increased by around 25% through the use of NdFeB magnets. By this means it is possible to combine high driving capacity with low wearout for the wire rope. Conventional traction sheaves with high driving capacity, such as Vgroove sheaves go along with fast wire rope deterioration because of the high local pressure stress on the rope

A Review on Automated Storage/ Retrieval Systems and Shuttle Based Storage/Retrieval Systems

Automated storage and retrieval systems are warehousing systems that are used for the storage and retrieval of products in both distribution and production environments. Shuttle based storage/retrieval systems are composed of elevators with lifting tables that are attached on a mast, shuttle carriers, buffer positions and the storage racks. It is observed that the shuttle based storage/retrieval systems increases the throughput capacity of the systems compared to automated storage/retrieval systems. Shuttle based storage/retrieval systems is relatively a new technology in automated storage and retrieval systems and usually works with aisle and tier captive shuttles. This new technology is mostly used for mini-load warehouses. The main body of the paper consists of an overview of literature discussing automated storage/retrieval systems and shuttle based storage/retrieval systems

A survey on performance analysis of warehouse carousel systems

This paper gives an overview of recent research on the performance evaluation and design of carousel systems. We discuss picking strategies for problems involving one carousel, consider the throughput of the system for problems involving two carousels, give an overview of related problems in this area, and present an extensive literature review. Emphasis has been given on future research directions in this area