MULTI AGV SCHEDULING PROBLEM IN AUTOMATED CONTAINER TERMINAL

ABSTRACT In this paper we propose a dynamic multi automated guided vehicle (AGV) scheduling method based on the scheduling properties of automated container terminal handling systems. In multi-AGV scheduling, the composition of AGV handling time and the precedence order of certain tasks are major constraints. Taking these into consideration, we design a genetic algorithm (GA) for a dynamic multi-AGV scheduling model to minimize completion time and standard deviation of handling time of quay cranes (QC), and validated the proposed model through numerical experiment. We expect this model to be significant for multi-agent scheduling of discrete production systems

Green vehicle technology to enhance the performance of a European port: a simulation model with a cost-benefit approach

In this paper, we study the impact of using a new intelligent vehicle technology on the performance and total cost of a European port, in comparison with existing vehicle systems like trucks. Intelligent autonomous vehicles (IAVs) are a new type of automated guided vehicles (AGVs) with better maneuverability and a special ability to pick up/drop off containers by themselves. To identify the most economical fleet size for each type of vehicle to satisfy the port's performance target, and also to compare their impact on the performance/cost of container terminals, we developed a discrete-event simulation model to simulate all port activities in micro-level (low-level) details. We also developed a cost model to investigate the present values of using two types of vehicle, given the identified fleet size. Results of using the different types of vehicles are then compared based on the given performance measures such as the quay crane net moves per hour and average total discharging/loading time at berth. Besides successfully identifying the optimal fleet size for each type of vehicle, simulation results reveal two findings: first, even when not utilising their ability to pick up/drop off containers, the IAVs still have similar efficacy to regular trucks thanks to their better maneuverability. Second, enabling IAVs ability to pick up/drop off containers significantly improves the port performance. Given the best configuration and fleet size as identified by the simulation, we use the developed cost model to estimate the total cost needed for each type of vehicle to meet the performance target. Finally, we study the performance of the case study port with advanced real-time vehicle dispatching/scheduling and container placement strategies. This study reveals that the case study port can greatly benefit from upgrading its current vehicle dispatching/scheduling strategy to a more advanced one

Control of free-ranging automated guided vehicles in container terminals

Container terminal automation has come to the fore during the last 20 years to improve their efficiency. Whereas a high level of automation has already been achieved in vertical handling operations (stacking cranes), horizontal container transport still has disincentives to the adoption of automated guided vehicles (AGVs) due to a high degree of operational complexity of vehicles. This feature has led to the employment of simple AGV control techniques while hindering the vehicles to utilise their maximum operational capability. In AGV dispatching, vehicles cannot amend ongoing delivery assignments although they have yet to receive the corresponding containers. Therefore, better AGV allocation plans would be discarded that can only be achieved by task reassignment. Also, because of the adoption of predetermined guide paths, AGVs are forced to deploy a highly limited range of their movement abilities while increasing required travel distances for handling container delivery jobs. To handle the two main issues, an AGV dispatching model and a fleet trajectory planning algorithm are proposed. The dispatcher achieves job assignment flexibility by allowing AGVs towards to container origins to abandon their current duty and receive new tasks. The trajectory planner advances Dubins curves to suggest diverse optional paths per origin-destination pair. It also amends vehicular acceleration rates for resolving conflicts between AGVs. In both of the models, the framework of simulated annealing was applied to resolve inherent time complexity. To test and evaluate the sophisticated AGV control models for vehicle dispatching and fleet trajectory planning, a bespoke simulation model is also proposed. A series of simulation tests were performed based on a real container terminal with several performance indicators, and it is identified that the presented dispatcher outperforms conventional vehicle dispatching heuristics in AGV arrival delay time and setup travel time, and the fleet trajectory planner can suggest shorter paths than the corresponding Manhattan distances, especially with fewer AGVs.Open Acces

Estudio sobre el avance del conocimiento en la automatización de las terminales portuarias de contenedores

[ES] Dada la alta competitividad del sector portuario, asi como la alta especializacion de los traficos, se intenta dar un valor an~adido a los clientes, y en especial a las navieras, que buscan tiempos de estancia bajos para poder maximizar la rentabilidad del buque. Por otro lado, y centrandose en el trafico de contenedores maritimos, los operadores de las terminales buscan una eficiencia en las operaciones, y en algunos casos, ademas, un aumento de la capacidad. Actualmente existe una tendencia de llevar a cabo la consecucion de los objetivos anteriores a partir de la automatizacion de la terminal. Esta tendencia de automatizacion ha crecido muy rapidamente desde la apertura en 1993 de la primera terminal de este tipo. Es por ello, que, este trabajo tiene como objetivo estudiar la evolucion de estas, enfocandose en los avances mas recientes, teniendo varias perspectivas. En primer lugar, se examina el avance en los distintos elementos que componen la terminal de contenedores automatizada, para posteriormente ver que problemas se han resuelto en el ambito academico. Finalmente se realizara un analisis de las terminales automatizadas y semiautomatizadas existentes.[CA] Donada l'alta competitivitat del sector portuari, aixi com l'alta especialitzacio dels tra`nsits, s'intenta donar un valor afegit als clients, i especialment a les navilieres, que busquen temps d'estada baixos per a poder maximitzar la rendibilitat del vaixell. D'altra banda, i centrant-se en el tra`nsit de contenidors maritims, els operadors de les terminals busquen una eficie`ncia en les operacions, i en alguns casos, a mes, un augment de la capacitat. Actualment existeix una tende`ncia de dur a terme la consecucio dels objectius anteriors a partir de l'automatitzacio de la terminal. Aquesta tende`ncia d'automatitzacio ha crescut molt ra`pidament des de l'obertura en 1993 de la primera terminal d'aquest tipus. Es per aixo`, que, aquest treball te com a objectiu estudiar l'evolucio d'aquestes, enfocant-se en els avancos mes recents, tenint diverses perspectives. En primer lloc, s'examina l'avanc en els diferents elements que componen la terminal de contenidors automatitzada, per a posteriorment veure quins problemes s'han resolt en l'a`mbit acade`mic. Finalment es realitzara` una ana`lisi de les terminals automatitzades i semiautomatitzades existents.[EN] The high competitiveness of port industry coupled with the specialization of maritime have resulted in rising the added value they place toward customers. The ones most affected are usually the shipping companies which seek short turnarounds to maximize the ship's cost-efficiency. Furthermore, -and focusing in the traffic of containers- terminal operator's aim is to ensure operations are efficient, and in some cases, to increase capacity. Current trends try to accomplish both goals with the automation of port container terminals. That trend of automation has rapidly expanded since its inception in 1993. This project will therefore study the evolution of said innovations, centring itself in the progress achieved recently. Firstly, this paper will discuss the evolution of the various elements that compose an automated terminal. Secondly, all problems present within said elements and already solved by the academia will be examined. Finally, an analysis of all existing automated and semi-automates terminals will be done.Baviera García, M. (2019). Estudio sobre el avance del conocimiento en la automatización de las terminales portuarias de contenedores. http://hdl.handle.net/10251/131784Archivo delegad

Improving container terminal efficiency: New models and algorithms for Premarshalling and Stowage Problems

El desarrollo del contenedor ha revolucionado el comercio marítimo de mercancías, permitiendo la manipulación de carga de diversos tipos y dimensiones con un costo reducido y disminuyendo el costo de importación de muchos productos, En la actualidad, aproximadamente el 90\% de la carga no a granel en todo el mundo se transporta en buques portacontenedores, cuyas capacidades han llegado a sobrepasar los 20000 TEUs (\emph{Twenty-foot Equivalent Unit}, unidad de medida correspondiente a un contenedor normalizado de 20 pies). Las terminales de contenedores tienen que hacer frente al creciente volumen de carga transportada, al aumento del tamaño de las naves y a las alianzas de las navieras. En este contexto, deben competir por menos servicios de barcos cada vez más grandes. Para ello, deben aumentar su eficiencia, optimizando los recursos existentes. En esta tesis se estudian dos problemas de optimización combinatoria, el problema de premarshalling y el problema de la estiba, que surgen en el patio y en el muelle de las terminales de contenedores, antes y durante las operaciones de carga y descarga de los buques, y cuya resolución deriva en una disminución del tiempo de atraque y, por lo tanto, en un aumento de la eficiencia de las terminales. El problema de premarshalling prepara el patio de contenedores antes de la llegada del buque, usando las grúas de patio cuando la carga de trabajo es mínima, con el fin de evitar un mayor número de recolocaciones a la llegada del buque y así acelerar los tiempos de servicio. El objetivo clásico de este problema ha sido reducir al mínimo el número de movimientos necesarios para eliminar los contenedores que bloquean la retirada de otros dentro de una bahía. De este modo, el número de movimientos se ha tomado como un indicador del tiempo de grúa. No obstante, en esta tesis se prueba que considerando como objetivo el tiempo real que la grúa emplea en realizar los movimientos, se puede reducir hasta un 24\% el tiempo total empleado. Para la resolución de ambos problemas, el premarshalling con función objetivo clásica y el premarshalling con la nueva función objetivo, se han desarrollado diversos modelos matemáticos y algoritmos Branch and Bound con nuevas cotas superiores e inferiores, reglas de dominancia y algoritmos heurísticos integrados en el proceso de ramificación. Por lo que respecta al problema de la estiba, se ha estudiado el problema multi-puerto que busca obtener un plan de estiba del barco de modo que se reduzca al mínimo el número total de movimientos improductivos en las operaciones de carga y descarga a lo largo de la ruta en la que presta servicio. Comenzamos estudiando el problema simplificado, en el que no se consideran restricciones de tamaño ni de peso de los contenedores, y progresivamente se van introducido restricciones más realistas, desarrollando modelos matemáticos, heurísticas, metaheurísticas y mateheurísticas. Estos procedimientos son capaces de resolver instancias de gran tamaño correspondientes a los barcos de mayor capacidad que se encuentran actualmente en el sector.The development of containers has revolutionized maritime trade by making it possible to handle various types and sizes of cargo at a reduced cost, lowering the import cost of many products to such an extent that it is sometimes cheaper to transport goods to the other side of the world than to produce them locally. Nowadays, about 90 per cent of non-bulk cargo worldwide is carried on container ships with capacities exceeding 20,000 TEUs (Twenty-foot Equivalent Units). Container terminals have to cope with the increase in the volumes of cargo transported, the ever-larger ships, and the consolidation of shipping companies. In this context, they have to compete for fewer calls of larger ships. Since they cannot simply increase the number of cranes indefinitely, they have to improve efficiency by optimizing the available resources. This thesis studies two combinatorial optimization problems, the premarshalling problem and the stowage problem. These problems arise in the yard and the seaside of container terminals, before and during the loading and unloading operations of the ships, and make it possible to reduce the berthing time and thus to increase container terminal efficiency. The premarshalling problem prepares the container yard before the arrival of the ship, using the yard cranes when the workload at the terminal is at a minimum to rearrange the yard in order to avoid container relocations when the vessel arrives and to speed up the service times. The classic objective of this problem is to minimize the number of movements required to remove containers blocking the retrieval of others within a bay. Thus, the number of movements has been used as an indicator of crane time. However, this thesis shows that considering the real time that the crane takes to perform the movements as the target, the total time spent by the crane can be cut down up to 24 per cent. To solve both problems, premarshalling with the classic objective function and premarshalling with the new objective function, this thesis develops several mathematical models and branch and bound algorithms with new upper and lower bounds, dominance rules and heuristic algorithms integrated in the branching process. With regard to the stowage problem, the multi-port problem is addressed, seeking to obtain a stowage plan for the ship so as to minimize the total number of unproductive moves in the loading/unloading operations along the trade route of the ship. We start with a simplified problem, in which no size and weight constraints are considered, and progressively introduce more realistic constraints, developing mathematical models, metaheuristics, and matheuristics. These procedures are able to solve very large instances, corresponding to the largest ships in service

Seventh Annual Workshop on Space Operations Applications and Research (SOAR 1993), volume 1

This document contains papers presented at the Space Operations, Applications and Research Symposium (SOAR) Symposium hosted by NASA/Johnson Space Center (JSC) on August 3-5, 1993, and held at JSC Gilruth Recreation Center. SOAR included NASA and USAF programmatic overview, plenary session, panel discussions, panel sessions, and exhibits. It invited technical papers in support of U.S. Army, U.S. Navy, Department of Energy, NASA, and USAF programs in the following areas: robotics and telepresence, automation and intelligent systems, human factors, life support, and space maintenance and servicing. SOAR was concerned with Government-sponsored research and development relevant to aerospace operations. More than 100 technical papers, 17 exhibits, a plenary session, several panel discussions, and several keynote speeches were included in SOAR '93

Optimizing the Performance of Robotic Mobile Fulfillment Systems

A robotic mobile fulfillment system is a novel type of automated part-to-picker material handling system. In this type of system, robots transport mobile shelves, called pods, containing items between the storage area and the workstations. It is well suited to e-commerce, due to its modularity and it's ability to adapt to changing orders patterns. Robots can nearly instantaneously switch between inbound and outbound tasks, pods can be continually repositioned to allow for automatic sorting of the inventory, pods can contain many different types of items, and unloaded robots can drive underneath pods, allowing them to use completely different routes than loaded robots. This thesis studies the performance of robotic mobile fulfillment systems by solving decision problems related to warehouse design, inventory and resource allocation, and real-time operations. For warehouse design, a new queueing network is developed that incorporates realistic robot movement, storage zones, and multi-line orders. For inventory allocation, we develop a new type of queueing network, the cross-class matching multi-class semi-open queueing network, which can be applied to other systems as well. Resource (re)allocation is modeled by combining queueing networks with Markov decision processes while including time-varying demand. This model compares benchmark policies from practice wit

A Polyhedral Study of Mixed 0-1 Set

We consider a variant of the well-known single node fixed charge network flow set with constant capacities. This set arises from the relaxation of more general mixed integer sets such as lot-sizing problems with multiple suppliers. We provide a complete polyhedral characterization of the convex hull of the given set

Aeronautical engineering: A continuing bibliography with indexes (supplement 217)

This bibliography lists 450 reports, articles, and other documents introduced into the NASA scientific and technical information system in August, 1987

Lessons learned on the Skylab program

Lessons learned in the Skylab program and their application and adaptation to other space programs are summarized. Recommendations and action taken on particular problems are described. The use of Skylab recommendations to identify potential problems of future space programs is discussed