Loader Crane Research Articles

Optimization of the mode of movement of the boom system of the loader crane

The article presents a method for solving the problem of eliminating vibrations of the load, which is fixed on a rigid articulated suspension at the time of simultaneous movement of two links of the boom system. The essence of the method is to optimize the mode of simultaneous movement of two links of the boom system of the loader crane with horizontal movement of the load during the start-up period. The problem is solved according to two optimization criteria, namely: according to the optimization criterion of the root-mean-square value of the generalized force and the optimization criterion of the root-mean-square value of the power of drive mechanisms. The developed criteria reflect the undesirable properties of the links of the boom system and drive mechanisms, so their value was minimized.
 The solution of the optimization problem is presented in a discrete form. For this purpose, the particle swarm optimization (ME-PSO) method was used. This helped to obtain discrete values of the kinematic and power characteristics of the boom system of the loader crane.
 Since the optimization criterion is an integral functional, the methods of the calculus of variations are used for its optimization. The solution of the variational optimization problem is presented in the form of many parametric functions that satisfy the boundary conditions of motion and minimize the obtained dimensionless criteria. For this purpose, the particle swarm optimization (ME-PSO) method was used. This made it possible to obtain the dependence of the optimal energy and power characteristics of the boom system and the drive mechanisms of the loader crane. The mode of movement of the boom system links obtained as a result of optimization improved the power and energy characteristics of the loader crane, which made it possible to increase its reliability and productivity.

ИССЛЕДОВАНИЕ НАПРЯЖЕННО-ДЕФОРМИРОВАННОГО СОСТОЯНИЯ МАТЕРИЛА В ОБЛАСТИ ВЕРШИНЫ ТРЕЩИНЫ, РАСПОЛОЖЕННОЙ В ЗОНЕ КОНСТРУКТИВНОГО КОНЦЕНТРАТОРА

The influence of the stress concentrator is studied due to the design features of the welded metal structure of a loader crane on the stress-strain state of the material in the fracture process zone. Within the framework of the research, a physical criterion using the basic mechanical properties of the material is applied. A normal tear-off crack is considered under uniaxial loading conditions. FEM analysis of T-joint and lap welded joint models, as creating the highest stress concentration in metal structures of loader cranes, is carried out. A comparative analysis of calculation results for models with a crack in the concentrator area and models with a crack in a smooth plate is performed. The influence of the concentrator and its several parameters on the stress stiffness at the crack tip is shown. A general averaged estimation of the concentrator influence on the material stress state in the fracture process zone is proposed. Recommendations on taking into account the presence of the concentrator in analytical calculations are given.

Online Deflection Compensation of a Flexible Hydraulic Loader Crane Using Neural Networks and Pressure Feedback

The deflection compensation of a hydraulically actuated loader crane is presented. Measurement data from the laboratory are used to design a neural network deflection estimator. Kinematic expressions are derived and used with the deflection estimator in a feedforward topology to compensate for the static deflection. A dynamic deflection compensator is implemented, using pressure feedback and an adaptive bandpass filter. Simulations are conducted to verify the performance of the control system. Experimental results showcase the effectiveness of both the static and dynamic deflection compensator while running closed-loop motion control, with a 90% decrease in static deflection.

Nonlinear Structural Analysis by Finite Element Method with Experimental Validation in a Rotatory Column for Loader Crane

Nonlinear Structural Analysis by Finite Element Method with Experimental Validation in a Rotatory Column for Loader Crane

TECHNOLOGY PROVIDING SECONDARY PROTECTION METAL STRUCTURES AGAINST CORROSION UNDER AGGRESSIVE IMPACT OF METALLURGICAL PRODUCTION

Research is aimed at the formation and development of innovative developments to increase the metal structures corrosion protection, as an important means of ensuring the quality and safety industrial facilities. The method determining the corrosion destruction signs, the procedure of monitoring and carrying out measures to diagnose the technical condition of lattice metal structures according to the level of corrosion hazard were adopted. The nomenclature indicators and control methods (conformity assessment) of determining parameters primary and secondary protection metal designs against corrosion is established. During this study, the lattice structures operational condition loader crane’s girder structure was considered. It is revealed that operation of the crane is carried out in difficult production conditions operating environment’s aggressive influence in combination with considerable dynamic loadings working operations loading technological process, unloading, sorting (averaging) of ore yard’s charge of blast furnace shop. Based on the study structures corrosion condition and operating conditions, measures have been developed to increase the durability ore-grab crane of the reloader. Based on the analysis of the principles of the ISO 9001 process approach, the development and implementation design solutions to extend the structures service life in aggressive environments of metallurgical production. It is proved that the procedure of making constructive and technological decisions, performance works on increase corrosion resistance promotes maintenance conditions of resource saving and technological safety industrial constructions. The principles process is offered to develop and implement design measures to extend the service life of structures in aggressive environments metallurgical production are proposed. Constructive and technological measures to ensure durability in accordance with the requirements of the building structure corrosion risk have been developed, which are determined by the critical indicators metal structures protection in the conditions corrosion influences within their limit values.

Anti-swing control of a hydraulic loader crane with a hanging load

In this paper, anti-swing control for a hydraulic loader crane is presented. The difference between hydraulic and electric cranes are discussed to show the challenges associated with hydraulic actuation. The hanging load dynamics and relevant kinematics of the crane are derived to create the 2-DOF anti-swing controller. The anti-swing controller is added to the electro-hydraulic motion controller via feedforward. A dynamic simulation model of the crane is made, and the control system is evaluated in simulations with a path controller in actuator space. Simulation results show significant reduction in the load swing angle during motion. Experiments are carried out to verify the performance of the anti-swing controller, showing good suppression of the payload angle in practice.

Modeling the swing of mobile loader cranes with anchor outriggers when operating on weak soils

The paper presents a dynamic model illustrating the swing of a mobile machine on a wheeled chassis equipped with a loader crane and anchor outriggers during loading and unloading operations. The model regards the interaction effect of the outrigger anchoring device with weak soil within the system “load – loader crane – chassis – outriggers – anchor devices – soil”. Possible variants of single and multiple step soil compaction and changes in its deformation characteristics in the area of the outrigger anchor device implementation are considered. The impact of the gaps formed during soil compaction on the swing parameters of a mobile machine during the swing of the boom of the loader crane is demonstrated as applied to a full-scale crane-manipulator. The rate of chassis tilt angle and swing period of the mobile machine increase during the loader crane operation with an increase in the gaps in the ground. The swing parameters during the initial stage of crane operation gradually increase for soils characterized by multiple compaction until these parameters reach some steady-state values determined by soil stiffness. Awareness of the steady-state value of the crane tilt angle amplitude achieved at the end of the process of weak soil compaction enables to reasonably assess the risk of a mobile machine overturning.

Experimental studies of the motion modes of the main boom and jib of loader crane

In order to increase the productivity and reliability of a hydraulic-powered loader crane, according to the normative-technical documentation regulating the safe operation of multi-link cranes, it is allowed to combine movements with the simultaneous movement of several links of the boom system. As a result, the paper considers a technique for conducting experimental studies in the plane of changing the boom system of a loader crane with a load. Experimental studies were carried out under the condition of simultaneous angular movement of the main boom and jib. To carry out experimental studies, an experimental installation of a hydraulic-driven loader crane was designed and manufactured. Measuring and recording equipment has been selected and adjusted. In the framework of experimental studies of the dynamics of movement of the boom system of a loader crane with a load, a control system for drive mechanisms has been developed, which makes it possible to realize the optimal modes of movement of the links of the boom system. As a result, experimental studies were carried out under the condition of simultaneous movement of the main boom and jib with a load at the end of the boom system. A package of data on real and optimal modes of movement of the links of the boom system of the loader crane was received. The processed data are presented in graphical form and a comparative analysis with real and optimal modes of movement is carried out. The developed method of experimental research has made it possible to determine the effect of the simultaneous movement of the boom and jib on the oscillations of the load, and the effect of the oscillations of the load on the dynamic loads arising in the boom system and the drive mechanisms of the loader crane.

Experimental studies of motion modes of the loader crane. Part 1

In order to increase the productivity and reliability of a hydraulic-driven loader crane, thepaper considers a technique for conducting experimental studies in the area of changing the boomsystem of a loader crane with a load in real and optimal modes of movement. At this stage,experimental studies were carried out under the condition of only the angular movement of the jib.To carry out experimental research, an experimental installation of a hydraulic-driven loadercrane was personally designed and manufactured. The measuring and recording equipment wasselected and adjusted.Within the framework of the experimental studies of the dynamics of movement of theboom system of a loader crane, with a load, a constructively modified spool with throttling slotswas developed, which improved the characteristics of the movement modes and made it possible torealize the optimal modes of movement of the links of the boom system.As a result, the experimental studies were carried out under the condition of angulardisplacement of the jib with a load at the end of the boom system both in real and in optimal modesof the movement. A data package was received for the real and optimal modes of movement of thelinks of the boom system of a hydraulic drive loader crane. The processed data were presentedgraphically and a comparative analysis of the real and optimal modes of movement was carried out.The analysis of the experimental studies carried out made it possible to calculate the effectof the jib movement on the oscillations of the load, and the actual effect of the load oscillations onthe dynamic loads that arise in the boom system and elements of the hydraulic drive of the loadercrane under different modes of movement.

HYDRAULIC LOADER CRANE – OPERATOR WORKPLACE RISK ASSESSMENT

The aim of this paper is to assess the risk to health and safety at work while working with a hydraulic crane mounted on a truck. After the risk assessment, appropriate preventive measures for healthy and safety of work are prescribed, together with a short manual on health and safety at work. The expert finding of the hydraulic loader crane was processed according to the Ordinance on the Manner and Procedure of Risk Assessment at the Work­place and in the Work Environment (Official Gazette of Republic of Serbia, no. 114/2014 and 102/2015).

Експериментальні дослідження режимів руху крана-маніпулятора з вантажем при суміщені рухів

In order to increase the productivity and reliability of a hydraulic-powered loader crane, according to the normative-technical documentation regulating the safe operation of multi-link cranes, it is allowed to combine movements with the simultaneous movement of several links of the boom system. As a result, the paper considers a technique for conducting experimental studies in the plane of changing the boom system of a loader crane with a load. Experimental studies were carried out under the condition of simultaneous angular movement of the jib and a decrease in the linear movement of the telescopic section. To carry out experimental studies, an experimental installation of a hydraulic-driven loader crane was designed and manufactured. Measuring and recording equipment has been selected and adjusted. In the framework of experimental studies of the dynamics of movement of the boom system of a loader crane with a load, a control system for drive mechanisms has been developed, which makes it possible to realize the optimal modes of movement of the links of the boom system. As a result, experimental studies were carried out under the condition of the simultaneous movement of the jib and the telescopic section with a load at the end of the boom system. A package of data on real and optimal modes of movement of the links of the boom system of the loader crane was received. The processed data are presented in graphical form and a comparative analysis with real and optimal modes of movement is carried out. The developed method of experimental research has made it possible to determine the effect of the simultaneous movement of the boom and jib on the oscillations of the load, and the effect of the oscillations of the load on the dynamic loads arising in the boom system and the drive mechanisms of the loader crane.

Adaptive Feedforward Control of a Pressure Compensated Differential Cylinder

This paper presents the design, simulation and experimental verification of adaptive feedforward motion control for a hydraulic differential cylinder. The proposed solution is implemented on a hydraulic loader crane. Based on common adaptation methods, a typical electro-hydraulic motion control system has been extended with a novel adaptive feedforward controller that has two separate feedforward states, i.e, one for each direction of motion. Simulations show convergence of the feedforward states, as well as 23% reduction in root mean square (RMS) cylinder position error compared to a fixed gain feedforward controller. The experiments show an even more pronounced advantage of the proposed controller, with an 80% reduction in RMS cylinder position error, and that the separate feedforward states are able to adapt to model uncertainties in both directions of motion.

Комплексна оптимізація режиму зміни вильоту стрілової системи крана-маніпулятора

The article presents a method for solving the problem, eliminating the oscillations of the load on the knuckle join suspension the simultaneous movement of two elements of the boom system, namely, lifting the jib and movement the telescopic section. The essence of the method is based on the optimization of the regime of simultaneous movement of two elements of the boom system of the loader crane during horizontal movement of the load during the start-up period. As an optimization criterion, a complex integral criterion was selected, which is a relative root-mean-square value of forces and powers in hydraulic drive cylinders. The developed criterion displays the undesirable properties of the boom system elements and drives mechanism, therefore, its values are minimized. Since the optimization criterion is an integral functional, variational calculus method are used to optimize it. The solution of the variational optimization problem is presented in the form of many parametric functions that satisfy the boundary conditions of motion and minimize the complex dimensionless criterion. For this purpose, the particle swarm optimization method (ME-PSO) was used. This made it possible to obtain the dependences of the optimal, energy and forces characteristics of the boom system and the drive mechanisms of the crane. The mode of movement of the boom system elements obtained as a result of optimization improved the forces and energy characteristics of the loader crane, which made it possible to increase its reliability and productivity.

Modal Analysis of Loader Crane with Variable Configuration

Modal Analysis of Loader Crane with Variable Configuration

Математична модель динаміки зміни вильоту стрілової системи крана-маніпулятора з вантажем при суміщені рухів

In order to improve the performance and reliability of the hydraulic loader crane according to the regulatory and technical documentation governing the safe operation of multi-link loader crane, it is allowed to combine movements with simultaneous movement of several links of the jib system. As a result, the paper considers the method of constructing a mathematical model in the plane of change of departure of the jib system of a link loader crane with a load. The functions of changing the kinematic and dynamic characteristics of the jib system while simultaneously moving its links are calculated. The construction of a mathematical model is performed using the Lagrange equations of the second kind. In this case, for the generalized coordinates of the model of a loader crane, the angular coordinates of the position of the links of the jib system and the angular deviation of the load. And the mechanical characteristics of the drive, presented in the form of quadratic dependencies between the acting forces and the speeds of movement of the hydraulic-cylinder rod. The control of the drive elements is represented as equations of the working fluid flow rate with a change in the flow area of the spool hydraulic distributor according to a linear law. As a result, the equation of motion of the loader crane was obtained, taking into account the influence of the inertial component of each link of the jib system and the influence of the oscillatory movement of the load on the dynamic loads of the metal construction and the hydraulic drive elements. The developed mathematical model makes it possible to theoretically determine the effect of the simultaneous movement of the jib and arm on the oscillations of the load, and the effect of the oscillation of the load on the dynamic loads arising in the jib system and elements of the loader crane drive.

Mathematical model of the dynamics varying the radius jib system loader crane at adjustment movement arm and telescopic section

Mathematical model of the dynamics varying the radius jib system loader crane at adjustment movement arm and telescopic section

Universal Mathematical Model of a Hydraulic Loader Crane

The paper presents the modeling technique of working processes of loader cranes installed on mobile machines using the developed universal mathematical model that considers complex interaction between the elements of a dynamic system ‘Working Body – Loader Crane – Basic Machine – Base Surface and Substructure – Control System – Environment’. The model considers the developed feedbacks between subsystems. The paper proposes the technique of imitating modeling of a loader crane loading during the entire operation period using the Monte-Carlo method and the universal mathematical model. The application of the developed approaches is shown on the example of a task concerning the general buckling of a mobile machine ACT-4-A equipped with a loader crane in the conditions of ground subsidence under a caterpillar.

Modeling the Dynamic Load of Loader Cranes Metal Structure with Excessive Backlashes in Sections Hinge Joints

The research objective presented in this paper is working out the mathematic model and methods of computer modeling the performance of hydraulic loader cranes with excessive backlashes in sections hinge joints. The mechanism for generating the additional impact load in joints is illustrated. It is based on analyzing the hinge pin displacement within the backlash and its periodic collisions with the limiting elements of a hinge joint. This method allows evaluating the degree of influence of the backlash value on the changes in the qualitative characteristics of the dynamic load of the cranes metal structure and the motion parameters of the conveying load. The computer modeling of the loader crane dynamics in its turning motion was performed. The excessive backlash at the point of connection of a load-handling device and a boom was analyzed. The comparative evaluation of the dynamic load of the crane metal structure was performed for two controlling cases: 1) the absence of a backlash; 2) the presence of a backlash (the backlash variation range is 0…2 mm). While the crane is in operation, some excessive backlashes may result in increasing the dynamic load of loader cranes metal structure twofold and more.

Using input shaping and pressure feedback to suppress oscillations in slewing motion of lightweight flexible hydraulic crane

This paper presents a method to actively reduce vibrations in the flexible mechanical structure of a hydraulically actuated vehicle loader crane. Based on information on the natural frequency and damping of a simplified model of the crane an input shaping scheme is set up to control the proportional valve leading to substantially reductions in oscillations. The method is compared and combined with a pressure feedback control of the proportional valve that actively suppresses transient variations in pressure. A full scale vehicle loader crane is used in the experimental verification of the method, and the motion of the tool point of the crane is measured by a high precision laser tracker. The results shown in this paper demonstrate that input shaping and pressure feedback are useful tools to minimize vibrations in hydraulically actuated flexible structures.

Comparison of Methods for Modeling a Hydraulic Loader Crane With Flexible Translational Links

When modeling flexible robots and structures for control purposes, most often the assumed modes (AMs) method is used to describe the deformation in combination with a floating reference frame formulation. This typically has the benefit of obtaining a low-order, but accurate model of the flexible structure, if the number of modes and AMs are properly chosen. The basis for using this method is, however, that the vibrations (deflections) are time and position independent, i.e., the expression is separable in space and time. This holds for the classic Euler–Bernoulli beam equation, but essentially does not hold for translational links. Hence, special care has to be taken when including flexible translational links. In the current paper, different methods for modeling a hydraulic loader crane with a telescopic arm are investigated and compared using both the finite segment (FS) and AMs method. The translational links are approximated by a single beam, respectively, multiple beam elements, with both one and two modes and using different mode shapes. The models are all validated against experimental data and the comparison is made for different operating scenarios. Based on the results, it is found that in most cases a single beam, low mode order approximation is sufficient to accurately model the mechanical structure and this yields similar results as the FS method.