Performance Of Cranes Research Articles

Fixed time robust control for tower cranes with unmatched disturbances and input saturation

SummaryTo address the challenging problem of fixed‐time anti‐sway and positioning control for tower cranes with uncertain disturbances and input saturation, a novel fixed‐time anti‐saturation robust algorithm is proposed. First, on the basis of a newly designed fixed‐time convergence system, a fixed‐time disturbance observer (FTDO) is developed to estimate the matched and unmatched disturbances. Then, an anti‐saturation compensator is employed to deal with the input saturation and make the control input leave the saturated region rapidly. Upon which, a novel non‐singular fast terminal sliding mode surface is presented. Furthermore, in order to ensure the stability of each subsystem, a hierarchical sliding mode surface taking into account unmatched disturbances and input saturation is designed. Finally, the FTDO based hierarchical sliding mode control law is introduced to improve the transient control performance and robustness of tower cranes. The fixed‐time convergence of the closed‐loop system is proved by Lyapunov technique. Numerical simulations for four scenarios demonstrate the validity of the presented control scheme and fastest convergence speed in comparison to the recently proposed fixed‐time control methods.

Safety Risk Assessment of Prefabricated Buildings Hoisting Construction: Based on IHFACS-ISAM-BN

Prefabricated buildings that are more environmentally friendly have been vigorously promoted by the Chinese government because of the reduced waste and carbon emissions during the construction process. Most of the construction processes of prefabricated buildings are completed in the prefabricated component factory, but the safety risks during the hoisting process cannot be ignored. In this paper, the initial framework of a Bayesian Network (BN) is obtained from the combination of the improved Human Factors Analysis and Classification System Model (HFACS) and BN. The improved similarity aggregation method (SAM) is used to calculate the prior probability of BN, which can better summarize and deal with the fuzzy judgment of experts on risk accidents. The improved SAM can consider both the weight of experts and the relative consistency of their opinions, which is of great significance for improving the reliability of BN inputted data. This paper uses the construction project in Sanya, Hainan Province, to verify the validity of the model. The results show that the calculation results of the model are basically consistent with the actual situation. The safety risk of this project is relatively low, and the premise of unsafe behaviors and unsafe supervision are the key risk factors of the project. In addition to maintaining good construction conditions and workers’ healthy states, it is also necessary to carefully check the performance of tower cranes and equipment such as spreaders. During the operation process of the tower crane, workers should avoid walking or staying within the hoisting range.

Analysis of construction sub-processes for the evaluation of the real performance of tower cranes

The productivity of work performed at construction sites is primarily dependent on the effective deployment and use of construction machinery. Nevertheless, manufacturers do not state the actual performance of their machinery because it is difficult to determine due to its dependence on the specific conditions present at each construction site. One of the most important machines used in the construction of buildings is the tower crane, which provides secondary transport of material onsite. In order to evaluate the effectiveness of the use of such machines using a deterministic or stochastic approach, a relatively extensive and exact set of data describing the activities of a given tower crane needs to be prepared. These data describe the real requirements of ongoing construction sub-processes with regard to the utilisation of tower cranes. This contribution concerns the analysis of key construction sub-processes during the building of monolithic reinforced concrete structures in connection with secondary transport at the construction site; in particular, it describes the preparation and processing of this data for the evaluation of real time requirements placed on tower cranes.

Research on the dynamic windproof and antiskid ability guarantee of port crane

This paper introduces the windproof and antiskid safety, types and working principles of dynamic windproof and antiskid devices in normal working conditions, analyzes the dynamic braking capacity and points out the deficiencies in the design, and puts forward relevant suggestion to provide basis for the subsequent evaluation of windproof and antiskid performance of port cranes.

Coupling the ILS optimisation algorithm and a simulation process to solve the travelling quay-crane worker assignment and balancing problem

In container terminals (CTs), the performance of quay cranes (QCs) is extremely impacted by their operators’ productivity, which makes the QC worker assignment a relevant element in the QC scheduling. Nevertheless, in the literature, this problem was tackled without considering the objectives of balancing operators’ workload and minimising the distance required to move between QCs, even though practitioners underline their importance in maintaining an efficient working environment. Accordingly, and based on a real-case study raised by a CT partner, this paper addresses a novel problem referred to as the travelling QC worker assignment and balancing problem. First, we propose a novel mathematical model with original constraints faced by the company to assign operators to QCs on a daily basis. Second, to find approximate solutions in a reasonable time, a constructive heuristic and an iterative local search (ILS) are proposed and tested on real datasets. We also propose a simulation-optimisation mechanism to evaluate the robustness of the solutions under real-time probabilistic perturbations. The proposed algorithms are integrated into a decision support tool, a network-linked application allowing users in a real CT to generate automatic assignments. The proposed simulation-optimisation procedure helps obtain balanced planning, avoid workload conflicts, and increase productivity.

Seismic analysis of uplift-available gantry crane subjected to extreme earthquake loads

This paper aims to investigate the uplift behavior coupled with the non-linearity both in material properties and in geometry deformations of a typical gantry crane under near-field ground motions. First, the highly nonlinear and time variable model considering the uplift-available boundary condition based on the theory of Mohr-Coulomb friction is established of the gantry crane using the OpenSees platform. Then, a series of time-history analyses on this model structure is performed under three near-field seismic loadings with different exceeding probabilities. Furthermore, the comparison between the uplift-available gantry crane and the fixed crane is also carried out to provide in-depth insight into the structural responses under different boundary conditions. Finally, coupling with the material and geometry inelastic behavior, the uplift response process is modeled in this paper and the seismic incident angle from 0 up to 360 degrees is also examined to quantitatively confirm the prioritization of uplift event and the other inelastic responses. And the new conception of uplift probability is first proposed herein to reveal the nature of uncertainty. It is found that uplift behavior plays an essential role in designing and evaluating the seismic performance of gantry cranes; further, the uplift response increases the seismic demand of the gantry crane structure and even causes collapse under strong ground motions.

Istraživanje srednje vrednosti potrebne energije, performansi i referentnih ciklusa slagačkih kranova

Automated storage and retrieval systems (AS-RS) are commonly used in intralogistic facilities and are often operated by stacker cranes. These stacker cranes are used in high-bay warehouses to move small load carriers, pallets and special load carriers. This paper presents an approach for the determination of the mean energy demand of stacker cranes, using a reference cycle. The examination of the reference cycles is based on a large scale simulation experiment with randomly generated stacker crane and rack configurations and operation tasks. The results permitted an analysis of the correlations between various parameters e.g. energy demand and performance of stacker cranes. Subsequently, three different reference cycles which allow an easy and fast calculation of the mean energy demand are developed and evaluated.

Safety evaluation for bridge crane based on FTA and AHP

Starting from the development status of the lifting machinery industry, this paper analyzes the data about safety accidents of bridge cranes, and identifies the assessment indicators affecting the safety performance of bridge cranes based on fault tree analysis (FTA), including fatigue factors, human factors, environmental factors, and management factors. Then, the weights of safety evaluation indicators are determined based on analytic hierarchy process (AHP). Finally, the safety evaluation system is established and demonstrated with use case diagram and role flow chart.

Adaptive Sliding-Mode Antisway Control of Uncertain Overhead Cranes With High-Speed Hoisting Motion

This paper proposes an adaptive sliding-mode antisway control law for uncertain overhead cranes with high-speed hoisting motion. Since the sway dynamics are disturbed by the trolley acceleration and hoisting velocity, antisway control law is designed based on the sliding mode control by defining a sliding surface in such a way that the trolley acceleration contributes to the sway dynamics as nonlinear damping in sliding mode. In addition, this nonlinear damping is designed such that it dominates the inherent damping coupled with the hoisting velocity so that the asymptotic stability of the sway dynamics can be achieved. To cope with system uncertainties such as system parameter variations, unknown actuator nonlinearities, unmodeled dynamics, and external disturbances, we design a fuzzy uncertainty observer and incorporate it into the sliding-mode antisway control law. Via the stability analysis and computer simulations, we show that the proposed control law guarantees the robust antisway performance of overhead cranes, regardless of hoisting velocity, even in the presence of system uncertainties.

Multi-Objective Dynamic Optimum Design of Crane Gearbox

The lower vibration and lightweight design is of great significance to large mechanical equipment. In order to achieve the best dynamic performance of cranes, this paper presents a multi-objective optimization approach based on finite element method. Firstly, the finite element model of coupling system consist of gear-rotor-bearing-housing is established. Subsequently, the transient response of the gearbox is studied using modal superposition method. Then with the purpose of reducing the vibration and preventing sympathetic resonance, a multi-objective optimizer is developed by employing a parametrical design language and obtained the optimal combination of design parameters after several iterations. The method and conclusions can be used as a reference of dynamic modification of large machineries.

Mathematical modelling of the container cranes under seismic loading and proving by shake table

This paper is concerned with modelling of the behaviour of container cranes under seismic loadings. For this purpose, physical and mathematical models are prepared. A six degrees-of-freedom non-linear mathematical model is developed in order to understand the dynamic behaviour of cranes under the seismic loadings. In order to determine the seismic behaviour of the container cranes against earthquakes, a 1/20 scaled crane model was designed and constructed. For the comparison of the models, the real earthquake records were used. The results are used to observe the destructive effects and compared with the period values of the most critical sections on the crane structure. When time and frequency domains are compared, it is seen that mathematical modelling of the container crane structure shows reasonable results under dynamic loadings. It will be available to take precautions and to increase seismic performance of cranes with the help of the developed dynamic model. Also, the developed mathematical model will be able to be used as a crane model in active vibration control studies in order to decrease the structural vibrations on container cranes.

Gantry Crane Scheduling with Interference Constraints in Railway Container Terminals

Abstract Railway container terminals, where gantry cranes are responsible for loading and unloading containers between freight trains and yards, are important hubs of hinterland logistics transportation. Terminal managers confront the challenge in improving the efficiency of their service. As the most expensive equipment in a terminal, the operational performance of gantry cranes is a crucial factor. In this paper, the gantry crane scheduling problem of railway container terminals is investigated. A mixed integer programming model which considers the effect of dwelling position dependent processing times is formulated. In addition, the safety distances, the travel times and the non-crossing requirement of cranes are incorporated in the mathematical model. A novel discrete artificial bee colony algorithm is presented to solve the intractable scheduling problem. Computational experiments are conducted to evaluate the proposed algorithm on some randomly constructed instances based on typical terminal operati...

자동화 컨테이너 터미널의 복수 장치장 크레인을 위한 실시간 작업 계획 수립

본 논문은 교행이 불가능한 두 대의 자동화 크레인을 운영하는 자동화 컨테이너 터미널의 장치장을 대상으로 국지적 탐색 알고리즘을 이용해 실시간 작업계획을 수립하는 방안을 제안한다. 제안방안은 실시간 제약조건을 만족시키기 위해 현재 이후 일정 시간의 작업만을 작업 계획의 대상으로 삼으며, 장치장의 동적인 작업 특성을 고려하여 새로운 작업이 요청될 때마다 작업 계획을 다시 수립한다. 또한, 교행이 불가능한 두 대의 크레인을 운영할 때 발생할 수 있는 크레인 간의 작업 부하 불균형을 해소하기 위해 작업 계획 과정에서 상대 크레인에 의한 사전 재취급과 사전 이적을 통한 두 크레인 간의 협업을 가능하게 하였다. 시뮬레이션을 이용한 실험 결과 제안 방안이 휴리스틱 방안에 비해 우수하며, 크레인 간의 협업이 작업 효율 향상에 도움이 됨을 확인하였다. This paper proposes a realtime scheduling method using local search algorithm for non-crossable yard cranes in automated container terminal. To take into consideration the dynamic property of yard crane operation and satisfy the real time constraint, the proposed method repeatedly builds crane schedule for the jobs in a fixed length look-ahead horizon whenever a new job is requested In addition, the proposed method enables the co-operation between yard cranes through prior re-handling and re-positioning in order to resolve the workload imbalance problem between the two cranes, which is one of the primary causes that lower the performance of yard cranes. Simulation-based experiments have shown that the proposed method outperforms the heuristic based methods, and the cooperation scheme contributes a lot to the performance improvement.

Reproductive performance and nest-site selection of White-naped Cranes Grus vipio in the Ulz river valley, north-eastern Mongolia

North-eastern Mongolia is an important breeding area for the globally threatened White-naped Crane Grus vipio. We studied reproductive performance and the influence of factors related to livestock grazing on reproduction and nest-site selection of the White-naped Crane population in the Ulz river valley, north-eastern Mongolia in 2000 and 2001. In 2001, 42 territorial pairs were found in 270 km of river basin. Recruitment was 18–22% resulting in 0.5–0.6 juveniles per territorial pair. The years 2000 and 2001 were within a dry period and recruitment might have been below the long-term average. White-naped Crane nests were significantly associated with river basin sections containing shallow water-bodies. The number and extent of shallow water-bodies are likely to be a limiting factor for breeding population size. Nest-sites in water-bodies were selected for high nest concealment, but nests were initiated even when concealing vegetation was not available. Only 26% of nests were >90% concealed suggesting that appropriate cover was often not available. Nest-sites were also selected for low grazing intensity. No correlation was found between hatching or fledging success and nest concealment or grazing intensity. Brood-size of successful pairs was higher if the home range was ungrazed, but further investigations are needed to clarify whether this was caused by absence of livestock grazing or other factors. Both because of internationally important numbers and because of a potentially high reproductive output, the study area is of high importance for the species.

Soft Lattice Truss Static Polynomial Response Using Energy Methods

A deterministic methodology is presented for developing closed-form dee ection equations for two-dimensional and three-dimensional lattice structures. Two types of lattice structures are studied: beams and soft lattices. Castigliano' s second theorem, which entails the total strain energy of a structure, is utilized to generate highly accurate results. Derived dee ection equations provide new insight into the bending and shear behavior of the two types of lattices, in contrast to classic solutions of similiar lattice truss structures. RUSSESare rigid skeletalframeworks utilized to provide sup- port for structures or equipment. They are generally composed of long slender members. Typically these members are joined with pin-connectors. Some attractive structural features of trusses are their low material-to-load-carrying characteristics relative to solid beams, ease of construction, and predictable behavior while incur- ring load. Truss designers rely on geometry, redundancy, and/or arch action to tailor and to optimize trusses for various load appli- cations. These and other design parameters play a crucial role in the performance of cranes, bridges, domes, and space-based structures. Various truss applications require designer evaluation of behavior foroperationalloading,vibrationalexcitations,orloadsduringtruss construction.Forpreliminaryanalysisorconceptualstudies,design- ers often study single-or double-layer planar latticetruss structures, which have regular and patterned geometries, to gain insight into theirstructuralbehavior.Latticestructuresareattractiveforstiffness and vibration analysis methods because their repetitive geometries are represented by mathematical models and numerical programsin a more accurate manner than trusses with curvature or local varia- tions.However, even the study of lattices encompasses a wide range ofanalysistechniques.Manyreportsandbookshavebeenpublished onlatticestiffnessanalysis,tailoringforload-transferefe ciency,and vibration response prediction. 1-8 One of themostcommon typesof analysis for lattice structures is the continuum approach in which a lattice' s stiffnessproperties are represented byan equivalent contin- uum model. However, continuum analysis is most useful for large lattices with many repeating cells. In general, transverse shear ef- fects are not included in the analysis of lattices; however, shear effects can be included with additional mathematical terms. This and other lattice analysis drawbacks have prompted this study. Objectives and Scope This paper provides a fundamental and integral approach to the study of lattice truss structures. First, a review of current lattice analysis methods is presented. Next, lattice geometry, symmetry, topology, and design are examined. Then lattice behavior or me- chanics are examined, and a new methodology for the analysis of Presented as Paper 97-1376 at the AIAA/ASME/ASCE/AHS/ASC 38th Structures,StructuralDynamics,andMaterialsConference,Kissimmee,FL, lattice structures is presented. The methodology provides insight into lattice design for strength or stiffness. Additionally, emphasis is placed on exact solutions of various lattice parameters such as nodal displacements and member loads. This limits the scope of the study but allows for greater insight into the behavior of selected lat- ticegeometries.TheinterestedreadershouldseeRef.9forcomplete details,validation using thee nite elementcode EAL,and additional lattice geometries. Specie cobjectivesofthisresearchare1 )todeveloptrussbeamge- ometries that under uniform loading exhibit classic fourth-, unique sixth-, and eighth-order behaviors for dee ection and 2 ) to develop simple closed-form, exact dee ection equations using Castigliano' s second theorem over the nodal domain of the uniform lattice struc- tures mentioned in objective 1.

Evaluation of the number of rehandles in container yards

The rehandling work influences the performance of transfer cranes significantly in a container terminal. The height and the width of a bay in the container stack are important decision variables in designing the storage configuration. And they are key factors which determine the average number of rehandles to pick up a container. In this paper, we propose a methodology to estimate the expected number of rehandles to pick up an arbitrary container and the total number of rehandles to pick up all the containers in a bay for a given initial stacking configuration. Simple tables and equations are provided to help the estimation of the number of rehandles.