Published Article / RFID can work in conjunction with sensors in material handling especially on a conveyor belt. A dozen different graded tagged products can be picked up by the RFID system in real-time and transported to respective chutes into automatic guided vehicles (AGV) for transportation to specific storage locations. The development of this system is now at an advanced stage. Our predictions to date show that the application of RFID in material handling in a manufacturing environment can assist in the fast flow of components throughout the assembly line beyond what available systems can do.

The motive of this research is to develop a good stacking method with an automatic material handling system and the procedures that can increase productivity, reduce production costs, and prevent labor injury. A diversity of products leads to a number of different kinds of stacking problems. Much research has been done focusing on two-dimensional arrangement for rectangles, circles or irregular shapes, and threedimensional regular-shaped objects such as rectangular boxes. To solve stacking problems, many algorithms such as the genetic algorithm, simulated annealing and other heuristic algorithms have been proposed. The three-dimensional stacking problem has a practical application in the transportation, manufacturing, and construction industries. There has been relatively little emphasis on three-dimensional irregular objects; however, stacking three-dimensional irregular objects has become more common in industry. In this thesis research, three heuristic algorithms are proposed to stack irregular stone pieces nested in a container with multiple layers. Primary functions of the heuristic algorithms include three major parts. First, it approximates irregular shapes to a cluster of straight lines. Secondly, it arranges the approximated angles one-by-one with the proposed step-by-step rule. Finally, it considers the weight of the stone pieces from the pixel calculation for reasons of stability. The first and second algorithms are based on the area and angle of the stone piece and the third one is based on the approximated weight of the stone. An automatic real-time stacking system including pneumatic devices, sensors, relays, a conveyor, a programmable logic controller, a robotic arm, and a vision system was developed for this study. The algorithms developed were tested by this automatic stacking system for better utilization. Three performance measures were presented in the experimental result. Comparisons between the results from three proposed algorithms and that from the bottom-back-left algorithm are made. Experimental data demonstrate that the utilizations and the stabilities of the three proposed algorithms are statistically better than that of the bottom-back-left algorithm. However, the cycle times of the three proposed algorithms have no statistical difference from that of the bottom-back-left algorithm. In addition, a statistical test between each proposed algorithm is also conducted. Both the utilizations and stabilities have statistical differences between each proposed algorithm while the cycle times do not. The results of this study show that the algorithm developed works effectively for solving the stone-pieces stacking problem.

Composants essentiels de tout ordinateur, les semi-conducteurs sont utilisés dans de nombreux secteurs. Les percées technologiques dans ce domaine imposent un rythme vertigineux aux industriels. Tous les deux ans environ, la capacité des puces est doublée et leur prix est divisé par deux. Le diamètre des plaquettes de silicium augmente et, regroupées en lots, les plaquettes sont plus lourdes à transporter. Les systèmes automatiques de transport (AMHS) se présentent comme une excellente alternative. Le prix très élevé des équipements de production fait que l’objectif est de saturer les capacités de production. Pour y parvenir, il est important que le système de transport et de stockage garantisse que les machines n’attendent pas des lots disponibles, et aussi que les lots n’attendent pas une machine disponible.Dans la littérature, la complexité du problème (jusqu’à 700 étapes de fabrication, flux réentrants, etc.) fait que les études de modélisation du transport se font avec de fortes hypothèses sur la production ou inversement. Pourtant, le transport est un service pour la production. Cette thèse propose une approche de modélisation permettant d'intégrer le plus fidèlement possible les contraintes de transport, production et stockage, afin d'améliorer les indicateurs clés de la production. Une analyse détaillée du système a permis de construire un modèle de simulation à événements discrets. Enfin, après une validation industrielle, l'étude complète du modèle a permis d'analyser les paramètres critiques de gestion du transport. Les résultats permettent une meilleure compréhension du système et mettent en exergue d'intéressantes perspectives de recherche. / Essential components of all computers, semiconductors are widely used in many sectors. Quick advances in these technologies force a challenging rhythm to manufacturers. Following the Moore’s Law, chip capacity doubles approximately every two years and prices are divided by two. Thus, the increase of the diameter of wafers to 300 mm makes them heavier to transport in lots. Automated Material Handling Systems (AMHS) are an excellent alternative to tackle this problem. Because of the high price of production equipment, the goal is to use production capacity as much as possible while avoiding to keep too much inventory. To reach this goal, it is important that the transportation and storage system ensures that machines do not wait for available lots, and also that lots do not wait for available machines. In the literature, due to the problem complexity (up to 700 steps, re-entrant flows, etc.), the modeling of transportation is made with strong assumptions on the production or vice-versa. However, transport is a service for production. This thesis aims at providing a modeling approach that allows the integration in details transport, production and storage constraints, in order to improve production key indicators. A detailed understanding of the system allows us to build of a discrete event simulation model which is, in our point of view, the best compromise between the necessary level of details and computational times. Finally, through industrial validations, the complete study of the model allows critical parameters of transport management to be analyzed. The results help to get a better understanding of the system and open interesting research perspectives.

In der Intralogistik führen technologieabhängig gekoppelte, drehzahlvariable Mehrmotorensysteme zu hohen Schwankungen im elektrischen Leistungsbedarf, der u.a. von der transportierten Gütermenge abhängt. Aufgrund der Überlappung der Lastanforderungen einzelner Verbraucher entstehen beträchtliche Lastmaxima, die das Versorgungsnetz belasten und eine Überdimensionierung der Infrastruktur erfordern. Ein räumlich ausgedehnter Gleichspannungsverbund in Kombination mit einem Energiespeichersystem sowie die Anpassung der Steuerung bieten Lösungen zur Verringerung der Netzanschlussleistung und des Energiebedarfs. Darüber hinaus ermöglichen solche Systeme eine effektive Rückgewinnung von potentieller und Bremsenergie. Am Beispiel eines Lagersystems mit Regalbediengeräten wird ermittelt, welche Reduktion des Netzleistungsbedarfs und Energieverbrauchs erreicht werden kann. Dabei werden ebenfalls die Auswirkungen auf die Durchsatzleistung des Systems untersucht. Dazu kommen Modelle des Bewegungsablaufes, der Komponenten der Antriebsstränge mit Abbildung von Mechanik, Getriebe, Motoren, Umrichter und der Speicher in einem Materialflussmodell zum Einsatz. Die Materialflusssimulationsumgebung wird dazu um die kontinuierlichen Modelle zu einem kombinierten Systemmodell erweitert und leistungsbegrenzende Steuerungsansätze im Zusammenwirken mit dem erweiterten Gleichspannungsverbund sowie den elektrischen Speichersystemen analysiert. Abschließend erfolgt die Ermittlung der Wirtschaftlichkeit der einzelnen Lösungen. Das Ergebnis ist ein Verfahren zur effizienten Betriebsweise von Intralogistiksystemen sowie eine Methode zur Dimensionierung eines räumlich ausgedehnten Gleichspannungsverbunds mit elektrischem Speicher. Zusammenfassend werden wirtschaftliche Maßnahmen identifiziert, die elektrische Lastmaxima reduzieren, die Schwankungen in der externen Energieversorgung verringern und die Energieeffizienz von Intralogistiksystemen verbessern. / In intralogistics, technologically linked, variable-speed multi-motor systems cause high fluctuations in electrical power demand due to variations in the amount of transported goods. These fluctuations often result in overlapping load demands by various consumers, which strain the supply network and require overdimensioning of infrastructure. To address this issue, a physically extended DC link, in combination with an energy storage system as well as adapted control, can reduce both grid power demand and energy consumption while allowing for the recovery of potential and braking energy. To evaluate the achievable reduction of grid power and energy demand, models were developed for individual components such as drive trains with motor, inverter, storage, axis coordination and material flow simulation with sequence control. An example of a warehouse system with storage and retrieval machines was used to determine the effects on throughput performance. To achieve this, the material flow simulation environment was extended to a combined system model, and performance-limiting control approaches were analyzed in interaction with the extended DC link and storage. Subsequently, economic feasibility of the individual solutions was determined. The result is a procedure for efficient operation of intralogistics systems and a methodology for dimensioning a physically extended DC link with electrical storage. The overall objective was to identify economic solutions that reduce electrical load peaks, balance external energy supply, and make intralogistics systems more energy-efficient. In conclusion, this study identifies economically viable solutions that can reduce electrical load peaks, balance external energy supply, and improve energy efficiency of intralogistics systems.