Automated Transport System Research Articles

Fast conflict detection using probability flow

Probabilistic conflict detection has recently attracted much attention from researchers due to its importance in safe automated transport systems; however, current methods struggle to accurately calculate in real-time the probability of conflict for complex vehicle maneuvers in cluttered environments. We present a formulation for the general probabilistic conflict detection problem using the flow rate of conflict probability at the boundary of a conflict zone. For Gaussian distributed vehicle states, we then derive a tight upper bound for the probability of conflict over a time period, which can be calculated in real-time using adaptive numerical integration techniques. We present two examples to illustrate the performance of this method: the first example shows that this method is very efficient for simple environments and the second example shows that this method can calculate the conflict probability upper bound in real-time even for complex vehicle maneuvers in cluttered environments.

Fully Automated Transport System for Local Intelligent Movement - FATSLIM

The aim of this project was to develop a transport system which ensures a smoother, safer and faster journey by road, thereby ensuring a better travel experience than encountered currently.This project was designed around the concept of transferring of control of the vehicle from humans to computers, which puts a check on the human factor involved in accidents. Also since the computers already know the way around the city, by virtue of the map of the city fed into them, the time taken to find out routes will also get cut down. As everything is controlled by computers, the person currently known as the driver shall have little to do as the vehicle moves towards the destination, ensuring a less exhausting journey. Since the controls of all the vehicles in one region lie in the hands of the same computer, therefore traffic in a region shall be coordinated with traffic coming from, and going to, other regions, also in case of road blockages, maintenance work or other sorts of diversions, the computer shall just guide the vehicle through a different route, all in all ensuring the time spent at traffic lights, traffic jams or any other delays shall be reduced.The idea of an automated transport system has been thought of before, but the advantages of this design over the predecessors are numerous. Although this is at a very basic stage and would need considerable developments before being in a position to actually be implemented, it is more efficient.

Leaky Waveguide for Train-to-Wayside Communication-Based Train Control

In guided urban automated transportation systems, the maintenance of a high-quality broadband train-to-wayside communication at all locations along the track poses a major problem. Several techniques are currently used. However, to achieve sufficient rates, a communication frequency range of 2-6 GHz is widely in use. At these frequencies, the natural propagation in tunnels usually works efficiently, but the communication through a leaky waveguide that is continuously laid along the track has several advantages. Over the required communication ranges of several hundred meters, between stations, such waveguides provide low longitudinal attenuation and remain of reasonable size. They also provide predictable communication ranges that could offer significant advantages over the natural propagation approach. This paper will theoretically and experimentally describe such a technical solution. Using ray-optical modeling of the radio propagation in a railway-type tunnel, the radiation characteristics of such a system will be evaluated. At the same operating frequencies, it will be compared with a conventional base solution using antennas separated a few hundred meters apart. An example of a recently operational implemented system will be presented.

Assessing public preferences for design and environmental attributes of an urban automated transportation system

This study investigates public preferences toward design and environmental aesthetic attributes of an automated transportation system—Personal Rapid Transit (PRT) in an urban setting. The goal of the study was to understand the perceived visual aesthetic quality of the PRT within diverse architectural and natural elements composing the town's main spatial and visual structure and to separate the various components that determine a cumulative visual experience. We utilized human perceptual judgments as indicators of visual aesthetic quality, and referred to a psychophysical method to assess the perceived visual aesthetic quality of the scenes. Perceptions were captured using a rank ordering process of most and least preferred scenes on presented panels and responses were analyzed using correlation and regression statistical techniques. Results indicate that specific design attributes such as pillar shape or size, and type of fascia, did not emerge as significantly influencing public perception, while the relationship between automated structure and vehicular infrastructure, and the position of the observer are particularly important. Overall findings indicate that studies conducted on automated transportation should consider the effect of context on the perception of the system. The findings improve our understanding of visual strengths and weaknesses of automated transportation structures within the urban environment and can be useful in the planning for similar transportation systems.

A field-based versus a protocol-based approach for adaptive task assignment

Task assignment in multi-agent systems is a complex coordination problem, in particular in systems that are subject to dynamic and changing operating conditions. To enable agents to deal with dynamism and change, adaptive task assignment approaches are needed. In this paper, we study two approaches for adaptive task assignment that are characteristic for two classical families of task assignment approaches. FiTA is a field-based approach in which tasks emit fields in the environment that guide idle agents to tasks. DynCNET is a protocol-based approach that extends Standard Contract Net (CNET). In DynCNET, agents use explicit negotiation to assign tasks. We compare both approaches in a simulation of an industrial automated transportation system. Our experiences show that: (1) the performance of DynCNET and FiTA are similar, while both outperform CNET; (2) the complexity to engineer DynCNET is similar to FiTA but much more complex than CNET; (3) whereas task assignment with FiTA is an emergent solution, DynCNET specifies the interaction among agents explicitly allowing engineers to reason on the assignment of tasks, (4) FiTA is inherently robust to message loss while DynCNET requires substantial additional support. The tradeoff between (3) and (4) is an important criteria for the selection of an adaptive task assignment approach in practice.

2301 港湾コンテナターミナルにおける自動搬送システムの信頼度設計(メンテナンス・信頼性・モニタリング,OS6 メンテナンス・信頼性・モニタリング)

2301 港湾コンテナターミナルにおける自動搬送システムの信頼度設計(メンテナンス・信頼性・モニタリング,OS6 メンテナンス・信頼性・モニタリング)

Improved design methodology for an existing automated transportation system with automated guided vehicles in a seaport container terminal

In this paper, we propose an improved design methodology to meet the changing demands of an existing automated container transportation system in which automated guided vehicles (AGVs) are used. This system is called an AGV transportation system. To achieve an improved design, it is essential to detect and correct any occurring bottlenecks. For this purpose, we exhaustively enumerate design proposals by constructing a logic tree. As a case study to verify the proposed methodology, we apply the methodology to an existing AGV transportation system. From the enumerated design proposals, we suggest design policies by considering the actual constraints of the transportation system. Finally, we redesign the transportation system as rapidly as possible. On the other hand, we keep system balancing into account; then, we derive a suitable demand and input number of AGVs under given specifications for a transportation system.

Advanced manufacturing simulation

PurposeThis paper aims to highlight the complex nature of automated guided vehicle (AGV) simulation model building, and especially how system modelling details affect the end results. This is an important issue in all of the transportation simulation systems, since they are service‐based by their nature, and additional inefficiencies create unanticipated performance downgrading.Design/methodology/approachThis paper uses a simulation approach, and simulated systems are based on a real‐life case study and on well accepted hypothetical simulation example.FindingsSimulation system boundaries are often neglected in the model building, and especially interface to inbound (and possibly outbound) material flow should be considered carefully; based on these research results, AGV investments are seen in an entirely different light, as system boundary is enlarged to contain more realistically interacting elements. Similar system boundary issues were found from the case study: interface with overhead gantry did not provide near optimal performance. The case study also revealed that high speed of AGVs is not necessarily worth additional investment; constraints exist in safety, acceleration and ability to turn in corners.Research limitations/implicationsThe findings are based on the simulation work and, to see the real implications, real‐life implementations on policy level are needed.Practical implicationsResults of this research provide more insights for manufacturing unit investments, and especially in the scope of automated transportation system use. Also changes in manufacturing flow management issues, after investing in, for example, AGV systems, are different from in less‐automated manufacturing units.Originality/valueThis research work provides more insights to simulation research work, especially from the perspective of transportation systems. Also implications arising from case study are unique as being compared to previous research in the field.

Internal transport in automated semiconductor manufacturing systems

This paper summarizes the main results presented by the author in his PhD thesis (Montoya-Torres 2005), supervised by Stephane Dauzeere-Peres, Jean-Pierre Campagne and Helene Marian, and defended on 29 November 2005 at the Ecole des Mines de Saint-Etienne and Universite Jean-Monnet. The thesis is written in French and is available upon request from the author. This work deals with a real-life transportation problem in the semiconductor industry. It proposes a new approach by integrating tactical and operational decisions for the control of the automated transport system. At the tactical level, the problem is modeled using integer linear programming models inspired from Location Theory. At the operational level, the solution obtained from the tactical optimization is coupled with a discrete-event computer simulation program and some policies for transportation operations are implemented and compared.

Dynamic transport scheduling under multiple resource constraints

This paper presents a heuristic for the dynamic vehicle scheduling problem with multiple resource capacity constraints. In the envisaged application, an automated transport system using Automated Guided Vehicles, bottleneck resources are (1) vehicles, (2) docks for loading/unloading, (3) vehicle parking places, and (4) load storage space. This problem is hard, because interrelated activities (loading, transportation, unloading) at several geographical locations have to be scheduled under multiple resource constraints, where the bottleneck resource varies over time. Besides, the method should be suitable for real-time planning. We developed a dedicated serial scheduling method and analyzed its dynamic behavior using discrete event simulation. We found that our method is very well able to find good vehicle schedules satisfying all resource constraints. For comparison, we used a simple approach where we left out the resource constraints and extended the processing times by statistically estimated waiting times to account for finite capacities. We found that our newly designed method finds better schedules in terms of service levels.

An efficient method of license plate location

License plate location is an important stage in vehicle license plate recognition for automated transport system. This paper presents a real time and robust method of license plate location. License plate area contains rich edge and texture information. We first extract out the vertical edges of the car image using image enhancement and Sobel operator, then remove most of the background and noise edges by an effective algorithm, and finally search the plate region by a rectangle window in the residual edge image and segment the plate out from the original car image. Experimental results demonstrate the great robustness and efficiency of our method.

Dispatching of overhead hoist vehicles in a fab intrabay using a multimission-oriented controller

The semiconductor manufacturing system has become one of the most important manufacturing systems in recent years. Intrabay automation for wafer transport is in high demand in a 300 mm foundry fab. The control of the transport system plays an important roles in manufacturing efficiency and the satisfaction of production strategy. In general, efficiency is the most important issue that has appeared in most research of automated transport systems. However, how to dynamically adjust the transport policy to meet the production strategy and to increase the transport efficiency as well seems to be more crucial to modern semiconductor manufacturing systems. In this paper, a fuzzy-logic-based multimission-oriented overhead vehicle dispatcher is developed. The vehicle dispatching rule is assigned in real-time according to the statistics of the manufacturing performance. In this manner, the dispatching rules can be adjusted according to possible high-risk lots so that most of the production strategies can be satisfied. If all of the lots meet the prescribed production strategies, then the nearest-job-first rule can be used to offer higher transport efficiency. In addition, the proposed vehicle dispatcher is also capable of deadlock-free operation, collision avoidance, and blockage prevention. Finally, this paper uses AutoMod simulation software to construct and evaluate the manufacturing models. By evaluating the simulation results, the proposed intelligent multimission-oriented vehicle dispatcher performs better performance than the others, and all of the production strategies are satisfied .

A small size continuous run industrial gamma irradiator

A new small size gamma irradiator is being set up at Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Brazil, with a revolutionary design. The developed technology for this facility consists of continuous tote box transport system, comprising a single concrete vault, where the automated transport system of products inside and outside of the irradiator utilizes a rotating door, integrated with the shielding, avoiding the traditional maze configuration. Covering 76 m 2 of floor area, the irradiator design is product overlap sources and the maximum capacity of Cobalt-60 wet sources is 37 PBq (1 MCi). The irradiator is being installed in a Governmental Institution and it will be used as a demonstration facility for manufacturers, who need an economic and logistic in-house irradiation system alternative. Also, it will be useful for supporting the local scientific community on development of products and process using gamma radiation, assisting the traditional and potential users on process validation, training and qualification of operators and radioprotection officers.

Dynamic one-way traffic control in automated transportation systems

In a project on underground freight transportation using Automated Guided Vehicles, single lanes for traffic in two directions are constructed to reduce infrastructure investment. Intelligent control rules are required to manage vehicle flows such, that collision is avoided and waiting times are minimised. In contrast to standard traffic control at intersections, these control rules should take into account significant driving times along the single lane (in our application up to 8 min). Whereas periodic control rules are often applied in traffic theory, we focus on adaptive rules such as look-ahead heuristics and dynamic programming algorithms. Numerical experiments show that our control rules reduce waiting times by 10–25% compared to a straightforward periodic rule. Dynamic programming yields the best results in terms of mean waiting times.

Hybrid I/O automata

Hybrid systems are systems that exhibit a combination of discrete and continuous behavior. Typical hybrid systems include computer components, which operate in discrete program steps, and real-world components, whose behavior over time intervals evolves according to physical constraints. Important examples of hybrid systems include automated transportation systems, robotics systems, process control systems, systems of embedded devices, and mobile computing systems. Such systems can be very complex, and very difficult to describe and analyze. This paper presents the Hybrid Input/Output Automaton ( HIOA ) modeling framework, a basic mathematical framework to support description and analysis of hybrid systems. An important feature of this model is its support for decomposing hybrid system descriptions. In particular, the framework includes a notion of external behavior for a hybrid I/O automaton, which captures its discrete and continuous interactions with its environment. The framework also defines what it means for one HIOA to implement another, based on an inclusion relationship between their external behavior sets, and defines a notion of simulation , which provides a sufficient condition for demonstrating implementation relationships. The framework also includes a composition operation for HIOAs, which respects the implementation relation and a notion of receptiveness , which implies that an HIOA does not block the passage of time. The framework is intended to support analysis methods from both computer science and control theory. This work is a simplification of our earlier HIOA model. The main simplification in the new model is a clearer separation between the mechanisms used to model discrete and continuous interaction between components. In particular, the new model removes the dual use of external variables for discrete and continuous interactions.

Scheduling vehicles in automated transportation systems

One of the major planning issues in large scale automated transportation systems is so-called empty vehicle management, the timely supply of vehicles to terminals in order to reduce cargo waiting times. Motivated by a Dutch pilot project on an underground cargo transportation system using Automated Guided Vehicles (AGVs), we developed several rules and algorithms for empty vehicle management, varying from trivial First-Come, First-Served (FCFS) via look-ahead rules to integral planning. For our application, we focus on attaining customer service levels in the presence of varying order priorities, taking into account resource capacities and the relation to other planning decisions, such as terminal management. We show how the various rules are embedded in a framework for logistics control of automated transportation networks. Using simulation, the planning options are evaluated on their performance in terms of customer service levels, AGV requirements and empty travel distances. Based on our experiments, we conclude that look-ahead rules have significant advantages above FCFS. A more advanced so-called serial scheduling method outperforms the look-ahead rules if the peak demand quickly moves amongst routes in the system.

Scheduling production tasks in a two-stage FMS

The paper is concerned with construction of a heuristic algorithm for an existing two-machine FMS. The system contains two dedicated machines with an automatic transport system served by one robot. There are three storage places: unlimited input and output buffers and a limited transitional one. The jobs are grouped into batches of identical parts. The parts are produced in a flow shop production environment. The parameters like release dates and set-up times for batches are taken into account. Furthermore, some of the parts need an additional operation processed by cooperatives between the first and second operation of the job. The heuristic algorithm has been constructed for the makespan criterion. Appropriate computational experiments validated the model and the algorithm proposed.

Progress in Laboratory Automation at Akita University Hospital

Akita University Hospital was established in 1971. Since then, we have been introducing automated analysis systems to deal with rapidly increasing tasks and demand in the clinical laboratory. In 1988, in collaboration with Hitachi Ltd. (Tokyo, Japan), we developed an automated analysis system composed of an automatic serum separating-aliquoting system connected to analysis systems through an automatic transport system. In 1998, the systems were integrated, enabling 97.6% of samples to be analyzed automatically. With this integrated system, information including the name of the patient, code number, age, gender, department, test to be performed and so on are all encoded on the label of the sampling tubes which are automatically labeled and sorted at the sampling division. The laboratory automation system succeeded in saving labor and time, yet there are still some areas that need improving. Namely, 1) minimizing the quantity of the sample required for analysis, 2) speeding up of the transportation, and 3) down-sizing the system. The development of less invasive, more compact and speedier analysis systems will make the clinical laboratory mobile or portable in the near future and will expand the working field of the clinical laboratory to remote areas and home-nursing services in the community.

Vector quantization for license-plate location and image coding

License-plate location in sensor images plays an important role in vehicle identification for automated transport systems (ATS). This paper presents a novel method based on vector quantization (VQ) to process vehicle images. The proposed method makes it possible to perform superior picture compression for archival purposes and to support effective location at the same time. As compared with classical approaches, VQ encoding can give some hints about the contents of image regions; such additional information can be exploited to boost location performance. The VQ system can be trained by way of examples; this gives the advantages of adaptiveness and on-field tuning. The approach has been tested in a real industrial application and included satisfactorily in a complete ATS for vehicle identification.

Neuro-Fuzzy Control of Converging Vehicles for Automated Transportation Systems.

For an automated transportation system like PRT (Personal Rapid Transit) System or IVHS, an efficient vehicle-merging algorithm is required for smooth operation of the network. For management of merging, collision avoidance between vehicles, ride comfort, and the effect on traffic now should be considered. This paper proposes an unmanned vehicle-merging algorithm that consists of two procedures. First, a longitudinal control algorithm is designed to keep a safe headway between vehicles in a single lane. Secondly, 'vacant slot and ghost vehicle' concept is introduced and a decision algorithm is designed to determine the sequence of vehicles entering a converging section considering total traffic flow. The sequencing algorithm is based on fuzzy rules and the membership functions are determined first by an intuitive method and then trained by a learning method using a neural net. The vehicle-merging algorithm is shown to be effective through simulations based on a PRT model.