Crane Movements Research Articles

Design of general LQR-ANN-controller of „crane-load” system. Part 1

The first part of the article describes the research concept and presents the results, which in the future allow the development of a LQR-neurocontroller of the movement of the dynamic "crane-load" system. For this purpose, the the problem of optimal control was stated. It uses a mathematical model in which the control function is considered as the rate of driving force change. This increases the order of the system by one. For individual components of the integral criterion, the weight coefficients were chosen and the values of the initial conditions were substantiated. The original problem of the synthesis of a LQR-controller is reduced to the Riccati equation. For one case, a solution to the Riccati equation was obtained and graphic dependencies corresponding to the obtained optimal control were built. The analysis of graphical dependencies made it possible to establish the disadvantages and advantages of the obtained optimal control. Among the advantages are the smoothness of the movement of the system and the provision of a zero value of the driving force at the beginning of the movement. This makes it possible to reduce the dynamic forces of the drive of the crane movement mechanism and its metal structure. Among the disadvantages of optimal control is a significant rate of increase of the driving force at the beginning of the movement, which can cause difficulties in the implementation of optimal control in practice, as well as an overshoot of the crane velocity. Multiple solutions of the Riccati equation made it possible to obtain datasets for training, validation, and testing of an artificial neural network, which is considered as a universal approximator of Riccati equation solutions. The process of data normalization and formation of training pairs is described. All data regarding the optimal values of the controller coefficients were obtained for load masses that varied within 60...25,000 kg and lengths of flexible suspension that varied within 1.2...12 m. In addition, the power of the weight coefficient varied within -5...-30, which corresponds to the minimization of the driving force rate.

Accident cause analysis for lifting prefabricated components of assembled buildings based on hybrid simulation technology from human factor perspective

PurposeThis paper aims to explore the characteristics of lifting accidents and the significance of influencing factors and explain the causes from the perspective of human factors, thereby achieving a more accurate understanding of and prevention of lifting accidents.Design/methodology/approachA mixed simulation model for prefabricated component lifting is established by combining discrete event simulation (DES) with the system dynamics (SD) method. In addition, essential parameters and relationships within the system dynamics model are determined through survey questionnaires. Finally, the human factors analysis and classification system (HFACS) is used to analyze the cause of the accident.FindingsThe results show that workers falling from height and workers struck by objects are the most frequent types of lifting accidents. In 2072 experiments, these two types of accidents occurred three and five times, respectively. Besides, the links of “crane movement,” “component binding,” “component placement” and “component unhooking” are particularly prone to lifting accidents. In addition, the completeness of emergency plans, failure to observe the status of the tower crane and lack of safety education and training have emerged as primary influencing factors contributing to the occurrence of lifting accidents.Originality/valueThe findings of the study can serve as a reference basis for practitioners, enabling them to preemptively identify possible risk accidents and adopt corresponding measures to prevent them, ensuring the safety and property of practitioners. Additionally, targeted suggestions and innovative ideas are provided to enhance the safety guarantee of the lifting industry and promote its healthy and stable development through a more concrete theoretical foundation and practical guidance.

TPE-Optimized DNN with Attention Mechanism for Prediction of Tower Crane Payload Moving Conditions

Accurately predicting the payload movement and ensuring efficient control during dynamic tower crane operations are crucial for crane safety, including the ability to predict payload mass within a safe or normal range. This research utilizes deep learning to accurately predict the normal and abnormal payload movement of tower cranes. A scaled-down tower crane prototype with a systematic data acquisition system is built to perform experiments and data collection. The data related to 12 test case scenarios are gathered, and each test case represents a specific combination of hoisting and slewing motion and payload mass to counterweight ratio, defining tower crane operational variations. This comprehensive data is investigated using a novel attention-based deep neural network with Tree-Structured Parzen Estimator optimization (TPE-AttDNN). The proposed TPE-AttDNN achieved a prediction accuracy of 0.95 with a false positive rate of 0.08. These results clearly demonstrate the effectiveness of the proposed model in accurately predicting the tower crane payload moving condition. To ensure a more reliable performance assessment of the proposed AttDNN, we carried out ablation experiments that highlighted the significance of the model’s individual components.

Priority rules for handling containers to improve energy consumption and terminal efficiency

AbstractThis paper addresses the optimization of the yard crane handling processes in a container terminal to reduce energy consumption and improve overall system performance. More precisely, the paper presents and evaluates different sequencing rules, based on predefined priorities, to organize the rail yard to minimize moves during the rail loading operations. The minimization of overall energy consumption and maximum tardiness are considered, simultaneously assessing these two components of the objective function to better understand how they interact and how they can be optimized together. As a novel issue in optimization, a hill climbing algorithm is implemented, searching for the yard configuration that most improves the efficiency of container handling while being able to integrate different management rules of the terminal. The reference case study is the PSA Pra terminal in Genoa, Italy. A full rail yard with known delivery times, and crane operating along a single stack, is the operative scenario. Random due time sequences are generated during test instances, while technical data of crane are used. Moreover, crane movements involve both loading and unloading along multiple axes. From the results, the best priority rules improve energy consumption and lateness of the initial configuration of the yard by up to 55%, thus allowing the terminal management to reorganize the storage areas accordingly and improve their efficiency. The proposed priority rules bridge the gap between theoretical optimization procedures and container terminal practices.

Calculation of the Required Power of Electric Motors for Overhead Crane Movement Mechanisms Using the Statistical Method

Calculation of the Required Power of Electric Motors for Overhead Crane Movement Mechanisms Using the Statistical Method

Optimizing berth-crane allocation considering tidal effects using chaotic quantum whale optimization algorithm

With the normalization of the global epidemic, shipping has gradually resumed, resulting in a surge in port throughput. Terminal managers are having great difficulty in making container ports be stable, orderly, and efficient. For small and medium-sized ports, making full use of the tidal water level to increase the operation time of large ships significantly improves the efficiency of port operations. Therefore, considering the impact of tidal factors on the operation of container ports, this paper firstly proposes a new berths and quay cranes allocation optimization model, T-B&QC, that minimizes the distance between the actual berthing berth and the preferred berth, the port time cost of ships and the number of quay crane movements as the optimization objectives, under constraints that consider tidal factors. Then, to solve the T-B&QC model using chaotic mapping and quantum theory, the Whale Optimization Algorithm (WOA) is integrated by using the Chaotic Quantum Rotating Gate Algorithm (CQRGA) and the Quantum Not Gate Algorithm (QNGA), whale coding rules are designed, and the Feasible-Integer Processing Algorithm (WF-IP) is established. Afterwards, the Chaotic Quantum Whale Optimization Algorithm, CQWOA, is proposed. Finally, the CQWOA is used to develop a new berth and quay crane allocation optimization method, T-B&QC_CQWOA. Subsequently, data from an actual seaport container port is used to test the reliability and superiority of the proposed distributing approach and the established optimizing algorithm. Numerical results demonstrate that the proposed distributing approach outperforms the classical distribution models that are selected herein, and the CQWOA yields a coordinated schedule of higher quality than the others in the process of solving the model.

Digital twin model of a large scale hot molten metal ladle pouring system

In steel-making processes, large quantities (frequently exceeding 300 t) of liquid metal are transferred between vessels. In Basic Oxygen Steel (BOS) making process, metal is poured from Hot Metal (HM) ladles, utilising overhead gantry cranes, into furnaces for further processing. Due to the large quantities of liquid metal poured, this operation poses significant safety concerns associated with metal spillage and releases of heat emissions. This can further lead to damage being caused to surrounding infrastructure. Pouring automation can reduce the likelihood of metal spillage, optimising ladle movement for reduction in heat emission releases. Given the hazardous nature of this operation, robust testing and evaluation of automated crane pouring movements is required prior to their application. A digital twin (DT) model of an overhead gantry crane/HM ladle system is presented here, intended to provide a safe testing environment for controlled pouring movement and serve as a testbed for control system design studies. Accurate crane movement is achieved using multi-body dynamics, solving for non-linearities present due to rigid joint frictional components. The flow rate of HM is estimated through the application of a dynamic model, allowing the modelling of system dynamics due to differences in HM pouring weights. The devised DT model is evaluated by simulating real crane movement and making a comparison on the resultant changing HM weight inside the ladle. The devised DT removes the need for construction of a physical model or performing tests directly on the HM pouring system.

Dynamical analysis of a 40 m span precast posttensioned concrete girder during lifting operations

AbstractCranes are employed to lift precast concrete girders during their construction. Presently, there is no recommendation for operational velocities during girder assemblage, particularly for long elements; simultaneously, several accidents have been reported during the transitory phase of girder motion. Since this mechanical problem has been examined in technical literature using a static approach, the present research study aims to investigate the dynamical behavior of a long, prestressed concrete girder by determining critical operational velocities according to crane movements. Prestressing cables' eccentricity and lifting loop position deviation were accounted for in 3D finite element simulations of a 40 m span precast prestressed concrete girder. Transient nonlinear analyses to obtain stresses and deflections were performed, so as to account for the large deformation behavior of the motion. A frequency domain approach was employed to analyze the time history results using the girder's natural frequencies obtained by modal analysis. The finite element model was developed to simulate upward, downward, and lateral girder movements. The most significant displacements and stresses were observed in the highest girder acceleration peaks, amplified by eccentricities. Safety against cracking and subsequent failure during vertical and lateral movements was ensured for crane operating accelerations of 0.02 g (v = 20 cm/s) and 0.007 g (v = 7 cm/s), respectively. Compared with the usual static analysis, for the critical case investigated, the inertial effect intensified the tensile stresses by 27 times, increased the compressive stresses by 11%, and increased the girder deflection by 3 times.

Energy-oriented crane scheduling in a steel coil storage

AbstractIn steel coil storages, gantry cranes store steel coils in a triangular stacking pattern and retrieve them to serve customer demand on time. The crane movements cause high energy consumption depending on the weight of the steel coils and the direction of the crane movement, which provides a starting point for more efficient crane operation in terms of energy consumption. However, current literature on crane scheduling in steel coil storages and neighboring domains mainly focuses on time-oriented objectives and neglects energy consumption. Therefore, we justify the problem of energy-oriented crane scheduling in steel coil storages and develop a mixed-integer linear programming model and a simulated annealing algorithm. The methods aim to minimize the energy consumed by crane movements while serving customer demand. We present extensive computational experiments comparing the energy-oriented approach against two popular alternatives from the literature. The energy consumption of crane movements can be reduced by 2–22% using energy-oriented crane scheduling compared to the alternatives with an identical customer service level. The simulated annealing algorithm solves instances of the size commonly found in the industrial practice of steel coil storage within an amount of time suitable for practical applications. Since extensive test instances for crane scheduling of steel coil storages have not been available thus far, we make our test instances accessible as a starting point for future research efforts.

Analysis of the Overhead Crane Energy Consumption Using Different Container Loading Strategies in Urban Logistics Hubs

This study addresses the critical gap in the literature regarding the energy efficiency of intermodal terminals in smart cities, mainly focusing on crane operations during train loading processes. Novelty’s contribution lies in developing a comprehensive simulation model in FlexSim, where quantitative analysis of crane energy consumption, factoring in container location in the storage yard, rehandling operations, and crane movement strategies were performed. Moreover, the analysis of hoist, trolley, and gantry movements was performed to evaluate their impact on overall container loading process energy efficiency. The findings reveal that the choice of train loading method significantly influences crane energy consumption, thereby affecting the operational costs, environmental footprint, and energy efficiency of the logistics hub in the form of an intermodal terminal. This research provides a methodology for assessing and enhancing the energy efficiency of intermodal terminals and highlights the broader implications for smart city sustainability goals, including reduced greenhouse gas emissions, lower operating costs, and improved transportation infrastructure. The outcomes of this research can possibly support smart city planners and logistics managers in making informed decisions to optimise intermodal terminal operations, contributing to urban areas’ sustainable development and economic resilience.

Vibration Analysis and Motion Control Method for an Under-Actuated Tower Crane

In this paper, we developed a solution for controlling a tower crane thought as a no-rigid system, and therefore able to have deformation and, during the motion, vibrations. Particularly, large tower cranes show high structural dynamics. Under external excitations, the payload tends to sway around its vertical position and this motion is coupled to the resulting dynamic vibration of the crane structure. These induced vibrations may cause instability and serious damage to the crane system. Furthermore, the energy stored in the flexible structure of a tower crane causes vibrations in the structure during the acceleration and deceleration of slewing movements. A crane operator perceives these vibrations as an unstable speed of the boom. Such behavior involves the control of the crane, particularly precise positioning and manual control of the crane movement at low pivoting speed. We define an Elastic model of the Slewing crane and analyze the bending and Torsional elasticity of the Tower, and the Jib Elasticity. With an approximated method, we calculate the natural wavelengths of the crane structure in the slewing direction. We consider the tower crane as a nonlinear under-actuated system. The motion equations are obtained considering both the normal vibration modes of the tower crane and the sway of the payload. An elastic model of the Slewing crane is achieved, modeling the crane jib as an Euler-Bernoulli beam. Even the payload dynamic is considered, developing an Anti-sway solution by the equation of the movement. We define an iterative calculation of the sway angles and obtain the corresponding velocity profiles, implementing two kinds of solution: an input-shaping control in open-loop, to be used with automatic positioning, and a “command smoothing” method in open-loop, used for reducing the sway of the payload with the operator control. These solutions lead to a reduction of the vibrations of the crane structure. As a consequence, the tower crane is not subject to the strong horizontal and vertical oscillations during the motion of the elastic structure.

Movement dynamics influence population monitoring and adaptive harvest management strategies in migratory birds

Informed population monitoring efforts are essential for sound management of harvested species, and adaptive strategies that provide detailed information to monitoring efforts often require data inputs from complimentary sources. Movement ecology information is seldom directly incorporated into population monitoring or adaptive harvest management strategies, yet can provide valuable information on species distributions, emigration and immigration rates, and aid in determining optimal population monitoring timing. The Rocky Mountain Population (RMP) of Sandhill Cranes is a harvested population subject to a stringent adaptive harvest management framework and an annual aerial survey to estimate population abundance, but movements of Sandhill Cranes during survey windows, and subsequent changes to harvest quotas based on their movement and distribution have not been investigated. We used seven years of GPS tracking data to estimate state-specific emigration and immigration rates, using a Bayesian multi-state capture-recapture model, among states within the RMP distribution to understand how seasonal crane movements may influence optimal aerial survey timing. We then leveraged these transition probabilities in conjunction with aerial survey count data to model how changes in aerial survey timing and movement-informed crane distribution would influence the current RMP Sandhill Crane adaptive harvest management model resulting in estimated changes to harvest allocation among states based on Sandhill Crane movement. We found that Sandhill Crane emigration from northern states began to increase the week of the aerial survey in late September, and continued to increase as autumn migration progressed into October. As expected, immigration to southern states began as emigration from northern states increased. Importantly, little movement among states occurred prior to the current aerial survey design timing. Overall, we found that current survey timing and shortly thereafter (∼1 week) did not greatly influence estimates of Sandhill Crane distribution, and did not greatly influence the harvest reallocation to each state until mid to late October (range of −42–+52 tag allocation change), much later than the current survey design would allow. Using GPS locations, we found that optimal population monitoring efforts could be improved to account for both detection and seasonal movements, while minimally influencing current adaptive harvest management strategies to stakeholders. Linking movement ecology with population monitoring efforts and subsequently adaptive harvest management strategies yields insightful information that can be beneficial for conservation planning, decision-making, and optimal species management of a migratory bird.

IMPROVEMENT OF THE GENERALIZED FORCE CRITERION OPTIMIZATION OF OVERHEAD CRANES MOVEMENT MODES

During the operation of overhead cranes, pendulum oscillations of the payload are often observed, which causes uneven movement of these cranes, their trolleys, loads on the ropes and power elements of the cranes, which, in turn, create various inconveniences during their operation, reduce the reliability of the functioning of both the crane as a whole and its individual elements. It is clear that all of these factors must be taken into account in the refined calculations of cranes (especially in the modes of their optimal (with the minimum driving force required for this) start/braking). The paper uses a standard methodology and scheme for calculating pendulum oscillations of a payload on the cables of an overhead crane, which are usually carried out within a two-mass model of a crane system. Further refinements and improvements to the above methodology have been made on the basis of a well-founded generalized force criterion for the quality of crane movement. The dependencies describing the law of motion of the crane system and the law of change in time of the applied driving force during the startup/braking stages were obtained, which satisfy the above-mentioned power criterion and ensure high-quality (smooth) movement of the system during its startup or braking. The law of motion of the crane rotation mechanism (crane drive) at its stopping, as well as the law of motion of the cargo at its lifting by the corresponding crane mechanism and sharp braking, at which the dynamic loads in the drive and in the crane rope, respectively, are minimized, is established. The results obtained in the work can be further used to clarify and improve the existing engineering methods for calculating the start-up modes of overhead cranes both at the stages of their design and in the modes of real operation.

Design and Implementation of a Control System for an Autonomous Reforestation Machine Using Finite State Machines

Reforestation is performed after the final felling as an important and often law-mandated step to ensure that wood production is sustainable. In Sweden alone, over 400 millions seedlings are planted annually. This work is physically demanding and the quality is uneven. Therefore, automatic production systems are under research and development. A necessary effort in this endeavor is presented in this paper: the development and evaluation of a mission supervisor utilized to control the mission and behavior of a full-scale autonomous forest regeneration machine tested in realistic environments. The mission supervisor is implemented in the Robot Operating System framework using a finite state machine package called SMACH. A terrain machine built as a research platform with an added full-scale forwarder crane is used as a base machine. First, we describe the scenario in which planting is conducted, whereupon we develop the composite tasks required as states. A simplified simulator then enables an intermediate step before field experiments. The system is implemented and operated in real time on a full-scale machine. Results show that the developed SMACH mission supervisor can be used as a sound basis for an autonomous forest regeneration machine and the chosen communication solution between different systems works well. The simulations show good agreement with the experiments. The results also show that crane movements take 70% of the machine time, emphasizing the importance of limiting crane movement, improving the actuator movement speed and integrating the composite solutions. Further development with a holistic approach is required before the concept can reach the prototype level.

Testing of a device for dynamic braking of crane mechanisms

The design and principle of operation of the developed device for dynamic braking of the mechanisms of movement of cranes are stated. The device allows to implement the following modes of dynamic braking: automatic; automatic with feedback from the motor rotor circuit; controlled. Bench tests of the device for dynamic braking were carried out. Experimental oscillograms of dynamic braking of a crane asynchronous electric motor in the indicated modes are recorded. Tests have shown that the minimum braking time is obtained at the fourth position of the controller (resistance of resistors in the rotor circuit was equal to 0.19 Ohm) in automatic mode. And the minimum number of engine revolutions before stopping (which characterizes the braking distance) - in the third position of the controller (resistance was 0.56 Ohms). The most effective control of the braking torque of the engine in the controlled mode is carried out at installation of the controller in the third or fourth positions. The device is recommended for smooth braking of bridge, gantry, tower, portal and other cranes. Automatic modes of dynamic braking are intended for the cranes working with identical or close on weight loadings (grab, magnetic, pouring and other cranes). The controlled mode of dynamic braking should be applied on the cranes carrying out loading and unloading works with freights of various weights. Tests have shown that the device has high reliability and stability of parameters when working in all these modes. In comparison with traditional braking by countercurrent braking, the device allows to reduce dynamic loads of metalwork by 20-30%, amplitude of fluctuations of loading more than twice, power consumption - almost by 18%.

Synchronous slew/translation positioning and swing suppression control for 4-DOF tower crane system

This paper introduces a method to navigate the tower crane movement and suppress the payload swing synchronously. Special error signals are introduced, which bring the coupling of dynamics among various states of the crane and enable the control to meet the synchronous operation in practice. The special angle-dependent energy functions are designed as the candidate sub-Lyapunov functions for decoupling the states. The controller is then stepwise designed with the help of the dynamics model. The stability of the control is proven in the Lyapunov sense. Extensive simulations and experiments have been carried out to demonstrate the effectiveness of the proposed nonlinear coupling control. A popular control approach in the literature is chosen to compare with the current work. It is found that the proposed control is quite effective in suppressing the payload swing while tracking the pre-determined path at the same time.

Monte‐Carlo simulation‐based analysis for structural reliability of the crane rail beam under stochastic crane movements and irradiation conditions

AbstractThis study presents a Monte‐Carlo simulation‐based approach to investigate how stochastic crane movements affect the structural reliability of the rail beam considering radiation effects. In the simulation, the rail beam loaded under a stochastically moving crane is discretized into 47 equispaced structural points for calculating its strain profile. Then the structural reliability at each structural point is calculated with the consideration of irradiation creep, represented as an accumulated strain over a given period of time. And the rail beam reliability is determined by the minimum value from the reliabilities calculated at different structural points, according to the weakest link principle. In our simulations, three candidate distributions, including the normal distribution, uniform distribution, and 3‐parameter lognormal distributions respectively, are applied to describe the stochastic distances of the crane. It can be seen from the simulation results that the rail beam reliability degrades with the most rapid rate when the crane distances follow a normal distribution, compared to the other two distributions. This paper offers a possible way of using the proposed Monte‐Carlo simulation‐based method to carry out reliability analysis and improvements for the rail beam working in extreme environments, such as irradiation conditions, with random operational tasks.

Simulation-based analysis for structural reliability of the crane rail beam under stochastic crane movements and irradiation conditions

This study presents a simulation-based approach to investigate the effects of stochastic crane movements on the structural reliability of the rail beam under radiation conditions. The rail beam is discretized into 47 equispaced structural points for strain profile calculation caused by a stochastically moving crane. The Normal distribution, Uniform distribution and 3-parameter Log-normal distributions are applied to describe the stochastic crane distances, respectively. The reliability at each structural point of the rail beam is defined with respect to the emergence of irradiation creep, which is calculated based on the accumulated strain over a given period of time. And the reliability of the rail beam is then determined by the minimum reliability calculated at different structural points, according to the weakest link principle. As shown by simulation results, the rail beam reliability degrades with the most rapid rate when the crane distances follow a Normal distribution, rather than the other two distributions. This offers a possible way to improve the reliability of the rail beam by avoiding clustered movements of the crane around the middle of the rail beam.

Static modes of an electromagnetic working shaft (EMWSh) and an electro-electromagnetic working shaft (EEMWSh) with the inclusion of a capacitor in the rotor circuit of the motors

In this paper, the issues of ensuring the statically stable operation of a two-motor electric drive are considered, a fundamentally new system of coordinated rotation of asynchronous motors based on an electromagnetic working shaft (EMWSh) has been developed. A distinctive feature of EMWSh is the connection of the rotor windings of two or more motors to the power windings of an induction rheostat (IR) and capacitors. The issues of practical application of EMWSh and electroelectromagnetic working shaft EEMWSh with the inclusion of a capacitor in the rotor circuit of motor systems in multi-motor electric drives of crane movement mechanisms and long conveyor lines are studied.

Tracking sarus crane movements in Cambodia and Vietnam reveals seasonal vulnerabilities and gaps in protected area coverage

The movements of 17 eastern sarus cranesGrus antigone sharpiiin Cambodia and Vietnam were tracked during both wet and dry seasons in 1998-2002 and 2015-2017, revealing previously unknown but important sites. Crane breeding territories were located in Cambodia’s northern dry deciduous dipterocarp forests, with territories of cranes captured in the Tonle Sap basin located further west and more likely to fall within protected areas than those captured in the Mekong Delta. During the non-breeding (dry) season, cranes returned to sites in which they had originally been captured. Most cranes initially used a different part of the same floodplain in the early stages of the dry season, but cranes from the Mekong Delta that nested west of the Mekong River would initially stop in the eastern Tonle Sap floodplains before continuing to the Mekong Delta floodplains. Protected area coverage of key dry season habitat within the Tonle Sap basin was lower than in the Mekong Delta. Out of 5 juveniles tracked in 2015/2016, 1 disappeared, 1 died and 1 was injured; 1 adult also disappeared. All mortality and disappearances occurred during the wet season and at least 1 mo after capture. Persistence of the eastern sarus crane will require improvement of protected area coverage of both breeding areas and previously unknown but important sites used during the dry season. In the dry season, engagement of farmers in conservation efforts is also important, as crane home ranges included agricultural areas even in the direct surroundings of protected wetland habitat.