Rubber Tyred Gantry Crane Research Articles

Modeling Power Flow in a Hoist Motor of a Rubber-Tired Gantry Crane

A method for calculating the power demand of the hoist motor in rubber-tired gantry (RTG) cranes with nonparallel cables has been developed to measure the energy consumption in a typical lift cycle. From measurements taken at the Port of Felixstowe, it has been observed that the peculiar geometrical characteristics of the hoisting mechanism cause the power demand to increase with the container height in constant rotor speed conditions. The change in the angle of the hoisting ropes causes an increase in torque load and power consumption. By using information extracted from the crane’s geometry, it has been possible to calculate the potential energy increase given the weight and vertical position of the container. The load torque on the hoist motor and the vertical speed of the mass have also been calculated, allowing for the modeling of the hoist motor power consumption when lifting containers with constant rotational speed. The proposed model has been compared to a constant power demand approximation, showing a higher accuracy for masses below 40 t.

Optimal Power Management Strategy for Energy Storage with Stochastic Loads

In this paper, a power management strategy (PMS) has been developed for the control of energy storage in a system subjected to loads of random duration. The PMS minimises the costs associated with the energy consumption of specific systems powered by a primary energy source and equipped with energy storage, under the assumption that the statistical distribution of load durations is known. By including the variability of the load in the cost function, it was possible to define the optimality criteria for the power flow of the storage. Numerical calculations have been performed obtaining the control strategies associated with the global minimum in energy costs, for a wide range of initial conditions of the system. The results of the calculations have been tested on a MATLAB/Simulink model of a rubber tyre gantry (RTG) crane equipped with a flywheel energy storage system (FESS) and subjected to a test cycle, which corresponds to the real operation of a crane in the Port of Felixstowe. The results of the model show increased energy savings and reduced peak power demand with respect to existing control strategies, indicating considerable potential savings for port operators in terms of energy and maintenance costs.

変則型形状コンテナターミナルにおけるブロックサイジング

This study addresses the container block sizing problem at container terminals with irregular configuration. New marine container terminals often have a rectangular configuration by making use of reclaimed land. However due to geographical reasons some terminals have an irregular configuration. At the irregular configuration terminal that Rubber Tyred Gantry crane (RTG) operated, the yard capacity for container stored depends on the aisle locations and number of aisles that yard trailers move. In this paper, we consider container block sizing problem as aisle arrangement problem at the arbitrary configuration, in order to maximize the storage capacity and minimize the standard deviation of travel distances by quay side location. From the computational results, we can find a part of solutions that proposed approach outperforms the existing one.

Multi-flexible Dynamic Modeling and Wheel Load Analysis of a Rubber Tired Gantry Crane in Container Cargo Working

Abstract This article describes the dynamic behaviors of a rubber tired gantry crane(RTGC) under typical load conditions which are used in the design of gantry cranes. In order to investigate the dynamic characteristics of an RTGC, we developed a finite element crane model for its huge structure. The finite element model was validated with the modal test results, e.g., natural frequencies and normal modes. And other components of RTGC were converted into detailed 3D CAD models and finally transformed to rigid body models in a dynamic simulation program ADAMS. The load conditions considered in this paper were a normal operating condition(OP1) and container hanging condition with no external loads. As a result, we could find there was large influence of crane's vibration owing to its structural stiffness and deformation. And the vibration of crane could made the movements of RTGC, which occurs crash or malfunction of crane works. Keywords :rubber tired gantry crane, finite element, multi-flexible body dynamics, simulation, wheel load

Sustainable port infrastructure, practical implementation of the green port concept

The overall idea and research interest related with the development of sustainable port infrastructure evolved around the core requirements of continuous reduction of negative environmental impacts without jeopardising economic growth. The growth of trade activities and need for competitiveness on the global market are forcing ports around the world to systematically and continuously evaluate all possibilities for the optimisation and related costs reduction. On the implementation level, the greatest challenge is how to empower workers, who operate machines and work on the shop floor, to achieve enduring performance improvements. Presented research work provides a methodological approach for finding realistic solutions to the problem of the future development challenges of seaports. The case study shown in this research represents a practical application of the green port concept with the emphasis on the overall energy efficiency improvement based on testing, deployment and demonstration of energy efficient solutions. Additional emphasis was placed on the state-of-the-art technologies and developing pilot initiatives based on modern energy solutions designed to improve efficiency in fuel consumption and emissions reduction in rubber tired gantry cranes.

A study of the tracking control of an transfer crane using nonholonomic constraint

The automation of container cranes is one of the significant factors of global competitiveness, by improving the celerity of distribution processing in container terminals. Most container terminals operate with Rubber-Tired Gantry Crane (RTGC) type container cranes. However, the RTGC displays various uncertainties, including slips and scarcities of air pressure of tires during tracking mode, and position error during suspension, and therefore it is difficult to secure reliability for the automation level, and systematic research developments remain in inadequate status. First, the problem of tracking control that tracks the route determined at the yard with high speed and accuracy must be solved, to achieve automation of the RTGC. Since it is virtually impossible to use the steering unit of the RTGC, there exist constraints of having to perform tracking control through the speed control of both drive units. Thus, the RTGC is a system with nonholonomic constraint, as the typical nonlinear system driven by tires. In this study, the nonholonomic system is applied to conduct the overall system modeling, through kinematic modeling and dynamic modeling of the RTGC. Furthermore, the sliding mode control technique is applied as one of the discontinuous time invariant control techniques, for the purpose of simultaneously accomplishing system stabilization, and overcoming model uncertainties. The gains of sliding planes will be analytically found by using the LMI technique, and performance of the proposed control unit will be confirmed through the experiment.

A Study on Variable Speed Generation System with Energy Saving Function

This paper presents development of variable speed generation (VSG) system with energy saving function. The rubber tyred gantry crane (RTGC) requires the power from diesel-engine. Significant fuel savings by reducing the engine speed can be achieved, because all of operation modes except hoisting are required lower power than rated value of engine. When low speed operation output voltage of generator is decrease until acceptable range of motor driver inverters and auxiliary load supplier. According to power demand engine speed is varying from 20 to 60Hz, and voltage is varying between 210Vac and 480Vac. When idle mode or low power operation dc/dc converter operates by constant output voltage control and inverters dc site voltage is compensated by it. This paper proposed 3-phase interleaved boost converter which has the same structure as the commercially available 3-phase inverter and current sharing capability. 400kW interleaved converter is designed and a performance of converter is evaluated through several experiments with a RTGC system. Energy saving VSG system can cut down fuel consumption by 36% and 21.3% at idle and unidirectional load operations.

Simulation Modeling and Analysis of Complex Port Operations with Multimodal Transportation

World trade has been increasing dramatically in the past two decades, and as a result containers exchange has grown significantly. Accordingly, container terminals are expanding to meet this increase and new container ports have opened. Ports with one or more container terminals are considered complex systems in which many resources, entities and transporters interact to achieve the objective of safely moving containers delivered by ships inland as well as loading containers delivered by trucks and rail onto ships. Ports with multimodal transportation systems are in particular complex as they typically operate with ships arriving to one or more terminals, multiple quay cranes, rubber tyred gantry cranes, trains, and trucks delivering containers of different types to terminals.With several resources of different types working and interacting, the system can be so complex that it is not easy to predict the behavior of the system and its performance metrics without the use of simulation. In this paper, a generic discrete-event simulation that models port operations with different resource types including security gates, space, rubber tyred gantry cranes, trains, quay cranes, and arriving and departing ships, trucks, and trains is presented. The analysis will entail studying various scenarios motivated by changes in different inputs to measure their impact on the outputs that include throughput, resource utilization and waiting times.

The Ultracapacitor-Based Regenerative Controlled Electric Drives With Power-Smoothing Capability

Modern controlled electric drive applications, such as lifts, port rubber tyred gantry cranes, and tooling machines, are characterized by high ratio of the peak to average power. Moreover, such applications have a need for braking at rated power. In ordinary drives, the braking energy, which represents 30%-40% of the consumed energy, is dissipated on a brake resistor. Apart from this “energetic” issue, the mains interruption, the input current quality, and the mains peak power are additional issues to be addressed. A novel ultracapacitor-based controlled regenerative electric drive with peak power-smoothing function is presented in this paper. The ultracapacitor with an interconnection dc-dc converter is used to store and recover the braking energy. In addition, the dc-dc converter controls and smooths the rectifier input power. In comparison to state-of-the-art solutions, the new solution has better performance regarding size, cost, and efficiency. The presented solution is theoretically analyzed and experimentally verified. The results are presented and discussed.

TOPSIS and AHP techniques for selecting the most efficient marine container yard gantry crane

Increasing global usage of containerised cargo in maritime trade imposes heavy traffic on both of the quayside and landside marine container terminals. Untangling this problem, terminal operators have to choose the most efficient operating system in their terminals. This study analyses the concept of Multiple Attribute Decision Making (MADM) for selecting the most efficient yard gantry crane in marine container terminals among three alternatives including Straddle Carrier (SC), Rail Mounted Gantry Crane (RMG), and Rubber Tyred Gantry Crane (RTG). Analytical Hierarchy Process (AHP) and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) are used as decision making tools during this research. The paper also provides an accurate comparison on the results of AHP and TOPSIS techniques.

주행상태에서의 가이드라인 계측 시스템 개발에 관한 연구

The handling ability of containers at the terminal strongly depends on the performance of the cargo handling system such as RTGC(Rubber Tired Gantry Crane) and RMGC(Rail Mounted Gantry Crane). This paper introduces a guide line measurement system on the operating condition, in which two camera are installed to detect the guide line. Because the line tracking is the basic technique for control system design of RTGC, it is necessary to develop a useful and reliable measurement system. If the displacement and angle of the RTGC relative to a guide line as the trajectory to follow is obtained, the position of RTGC is automatically calculated. Therefore, in this paper, a camera-based measurement system is introduced. The proposed measurement system is robust against light fluctuation and cracks of the guide line. This system consists of two camera and a PC which are installed at the lower side of the RTGC. Two edges of the guide line are detected from an input image taken by the cameras in the moving state, and these positions are determined in a Hough parameter space by using the Hough transformation method. From the experimental results, the accuracy and usefulness of the proposed system is evaluated by comparing other instruments.

실외 주행환경을 고려한 카메라 기반의 RTGC 위치계측시스템 개발

This paper describes a camera-based position measurement system for automatic tracking control of a rubber Tired Gantry Crane (RTGC). An automatic tracking control of RTGC depends on the ability to measure its displacement and angle from a guide line that the RTGC has to follow. The measurement system proposed in this paper is composed of a camera and a PC that are mounted on the right upper between front and rear tires of the RTGC's side. The measurement accuracy of the system is affected by disturbances such as cracks and stains of the guide line, shadows, and halation from the light fluctuation. To overcome the disturbances, both side edges of the guide line are detected as two straight lines from an input image taken by the camera, and parameters of the straight lines are determined by using Hough transform. The displacement and angle of the RTGC from the guide line can be obtained from these parameters with the robustness against the disturbances. From the experiments with the disturbances, we found the accurate displacement and the angle from the guide line that have the standard deviations of 0.95 pixels and 0.22 degrees, respectively.

Design and development of an intelligent context-aware decision support system for real-time monitoring of container terminal operations

This paper describes a case study of the research and development of an intelligent context-aware decision support system (ICADSS) prototype for real-time monitoring of container terminal operations in Hong Kong. We present the system design and development of the prototype system, and discuss the experiences and lessons learned. To the best of our knowledge, this study is the first identifiable application of an intelligent context-aware decision support system for the real-time monitoring of container terminal operations reported in the academic literature. The intelligent context-aware decision support system employs ZigBee-based ubiquitous sensor network (USN) technology. In this study, an ICADSS prototype was built and implemented in a real world setting. The results of the system prototype evaluation are satisfactory and support the contention that it is more effective in supporting the real-time tracking and tracing of container trucks, quay cranes, and rubber-tired gantry cranes in a container terminal. The results also validate the practical viability of the proposed system architecture. Given the contextual details of the study, we present the lessons learned from developing and operating the system in a container terminal and provide suggestions for further research. We hope that the proposed system architecture and developed prototype system can help both practitioners and academics in the further use and research of intelligent context-aware decision support systems.

RTGC 주행제어를 위한 카메라기반 가이드라인 위치계측시스템 개발

The handling ability of containers at the terminal strongly depends on the performance of the cargo handling system such as RTGC(Rubber Tired Gantry Crane). This paper introduces a new guide line position measurement method using a camera for the RTGC which plays a important role in the harbor area. Because the line tracking is the basic technique for control system design of RTGC, it is necessary to develop a useful and reliable measurement system. If the displacement and angle of the RTGC relative to a guide line as trajectory to follow is obtained, the position of RTGC is calculated. Therefore, in this paper, a camera-based measurement system is introduced. The proposed measurement system is robust against light fluctuation and cracks of the guideline. This system consists of a camera and a PC which are installed at the lower side of the RTGC. Two edges of the guide line are detected from an input image taken by the camera, and these positions are determined in a Hough parameter space by using the Hough transformation method. From the experimental results, high accurate standard deviations were found as 0.98 pixel of the displacement and 0.24 degree of the angle, including robustness against lighting fluctuation and cracks of the guide line also.

슬립을 고려한 트랜스퍼 크레인의 주행제어에 관한 연구

Abstract: The most important thing in the container terminal is to handle the cargo effectively in the limited time. To achieve this object, many strategies have been introduced and applied to. If we consider the technical trends and environment of the automated container terminal, it is necessary that the systems for cargo handling are equipped with more intelligent control technologies. To cope with this tendency, from the middle of the 1990's, the automated RMGC (Rail-Mounted Gantry Crane) and RTGC (Rubber-Tired Gantry Crane) have been developed and widely used to handle containers in the yards. Recently, in these cranes, the many equipments like CCD cameras and sensors are mounted to cope with the automated terminal environment. If we want to obtain more efficient handling performance, the modelling, tracking control, anti-sway system design, skew motion suppressing and complicated motion control problems must be considered in the control system design and application process. Considering these problems, in this paper, the system modelling with the tire slip and a tracking control approach are proposed. Especially, we design the tracking control system based on the 2DOF servosystem design approach to cope with undesirable disturbance input. The experiment results show the desirable performance and usefulness of the designed control system. Keywords: rail-mounted gantry crane, rubber-tired gantry crane, automated container terminal, 2DOF servosystem, observer, tracking control

Research of Supercapacitor Voltage Equalization Strategy on Rubber-Tyred Gantry Crane Energy Saving System

A model for supercapacitor voltage equalization strategy is analyzed, and on this basis a supercapacitor voltage equalization method for Rubber Tyred Gantry Crane (RTG) energy saving system is proposed, namely active voltage equalization method based on Buck-Boost converter. The equalizing speed of the proposed method is fast. Firstly, the working principle and process of the voltage equalization circuit is analyzed in detail. In addition, design of active voltage equalization circuit parameters and control strategy are given. Finally, simulation analysis of the series connection of supercapacitors module is performed. Results show that this method for equalizing voltage can avoid over-voltage of each cell and possess practicable and high value for supercapacitor RTG energy saving system.

Design of an Automated Container-Handling System in a Seaport Terminal Considering Operating Machine Performance

To provide a highly efficient and automated container-handling system in a seaport terminal, it is necessary to take into account the performance of operating machines, such as quay container cranes, automated guided vehicles, and rubber-tired gantry cranes, in addition to their fleet sizes. In this paper, we introduce these parameters as design objectives. However, this is a serious combinatorial design problem that consists of the objectives presented above. Moreover, it is not always true that a terminal system, in which larger numbers of machines are used with upgraded operation performance, obtains higher throughput. It thus becomes a challenge to identify a design parameter with an impact on the system throughput and to find the most reasonable combination of design parameters. In this issue, we apply a design strategy to this challenge and then modify a previously proposed hybrid design methodology. As a case study for the system design, we determine the combinatorial design solutions to meet given demands. Finally, we show the effectiveness of the system design in consideration of the machine performance.

Yard Crane Management by Simulation and Optimisation

In a terminal container the yard management is a critical and dynamic component that requires governance and flexibility to adapt to and address even the most complex issues arising out of yard planning and operations. With particular reference to the assignment and deployment of Rubber Tired Gantry Cranes among yard blocks, an optimisation model is proposed. Its purpose is to determine the block pairs between which yard cranes will be transferred during the period under examination in order to satisfy the crane capacity requirements and minimise the total cost for block matching and crane activation. The use of this stand-alone optimisation approach is then extended by introducing the architecture of an integrated framework, which includes both optimisation and simulation techniques and is based on an all-inclusive queuing network representing the main subsystems of a terminal. During scenario analysis, the framework is designed to evaluate which policy for assigning yard cranes to yard blocks is best for meeting the dynamic and constantly updating requirements of the yard subsystem. To this purpose, some Ranking and Selection (R&S) techniques are considered. The ongoing numerical experiments mean to demonstrate how a newly proposed R&S procedure is sufficiently robust for use in practice.

Development of DPF and DeNOx Combined for Rubber-Tired Gantry Crane (RTG)

Recently, the regulation of the diesel engine (DE) exhaust has become stricter due to environmental considerations. It is now required to take countermeasures against DE exhaust on the material handling of equipment in the container terminal. Mitsui Engineering & Ship Building Co., Ltd. (MES) has proposed to the market a solution for DE exhaust of Rubber Tired Gantry Crane (RTG) and has developed a combined system of Diesel Particulate Filter (DPF) and NOx Reduction System (DeNOx) . A Continuous Regenerating Trap method is newly applied for DPF. An Urea Injecting SCR method is used to improve the DeNOx performance of the system. With these new methods, a target reduction rate of 50% for PM, and 80% for NOx have been achieved. This confirmed by measurement and analyzing field data of the RTG in operation. The system was mounted on the RTG and its durability and reliability were verified through the pattern test for each operation mode, and throughout 1, 500 hour operations. In 2006 MES acquired the certification of DPF from the U. S. Environmental Protection Agency (USEPA) and the California Air Resource Board (CARE) . In 2007 orders were placed by the Port of Los Angeles (POLA) .

트랜스퍼 크레인의 주행제어에 관한 연구 : 관측기 설계 및 실험적 연구

The most important thing in the container terminal is to handle the cargo effectively in the limited time. To achieve this object, many strategies have been introduced and applied to. If we consider the automated container terminal, it is necessary that the cargo handling equipments are equipped with more intelligent control systems. From the middle of the 1990's, an automated rail-mounted gantry crane(RMGC) and rubber-tired gantry crane(RTG) have been developed and widely used to handle containers in the yards. Recently, in these cranes, the many equipments like CCD cameras and sensors are mounted to cope with the automated terminal environment. In this paper, we try to support the development of more intelligent automated cranes which make the cargo handling be performed effectively in the yards. For this plant, the modelling, tracking control, anti-sway system design, skew motion suppressing and complicated motion control and suppressing problems must be considered. In this paper, the system modelling and a tracking control approach are discussed. And, we design the tracking control system incorporating an observer based on the 2DOF servosystem design approach to obtain the informations of the states. The experiment results show the usefulness of the designed control system.