Trolley Motion Research Articles

Dynamic Modelling and Feed-forward Control of an Overhead Crane

The article presents: modelling, simulation, and controller design of a laboratory overhead crane system. A nonlinear model was developed using Lagrange equation and linearization process is performed for the purpose of analysis and controller design. Accuracy of the linear model is assessed by comparing simulation results of nonlinear and linear dynamic equations. A feed-forward control based on a low-pass filter was designed based on the crane dynamics. The controller performance is discussed in terms of trolley position response and payload sway reduction. The proposed control approach is able to suppress the payload sway, but at the expense of a slight delay in the trolley motion

An enhanced coupling optimal trajectory planning for bridge cranes

For the bridge crane system, the control objective is to deliver the cargo to the target location quickly, accurately, and with the smallest possible swing. Therefore, this paper proposes a novel signal-based trajectory planning approach and designs the corresponding tracking control strategy. The approach ensures that the payload can be transported smoothly in the shortest time and effectively suppresses and eliminates payload swing throughout the process. Specifically, a novel signal with enhanced coupling is first constructed, and then the system model is transformed into the system represented by the signal. The system is further discretized into critical control points, the trajectories are designed, and the optimization problem is formulated using the constraints obtained from the discrete system. Moreover, the proposed method enhances the coupling between the trolley motion and the payload swing angle, which reduces computational accuracy loss and improves the transient performance of the system. Additionally, a tracking controller is designed to verify the feasibility of the trajectory and enhance the tracking effect of the trajectory. Finally, the effective control performance of the proposed method is verified by comparing it with existing methods.

An emergency braking method with swing suppression and safety limits consideration for double pendulum cranes

In this paper, considering the emergency braking problem for double pendulum crane systems, we propose a swing suppression guaranteed braking method with safety limits consideration, whose performance is also theoretically proved. Since the workspace for double pendulum cranes may be complex, while the transported payload may be large, it is of great significance to design proper emergency braking methods to make the entire double pendulum crane brake quickly and avoid possible accidents. By carefully analyzing the crane dynamics and taking into account the important swing suppression objective, coupling enhanced terms are designed based on the coupling behavior between the trolley motion and the swing angles. Then the coupling enhanced terms are combined with crane mechanical energy function, which further introduces swing angle-related feedback terms and achieves better swing suppression performance. Furthermore, safety limits are also taken into consideration by designing a special barrier function-like term, which can restrict the payload and hook horizontal positions in permitted domains. Based on all these terms, the swing suppression guaranteed braking method is designed with rigorous mathematical analysis proposed to shown its proper performance. To the best of our knowledge, it is the first emergency braking method for double pendulum cranes. Experimental tests are also implemented by using a hardware crane testbed, which further verify the effectiveness of the proposed method.

Minimization of oscillations of the tower crane slewing mechanism in the steady-state mode of trolley movement

Minimization of oscillations of the tower crane slewing mechanism in the steady-state mode of trolley movement

MODELING AND OPTIMIZATION OF THE PROCESSES OF MOVEMENT AND ACCELERATION OF THE OVERHEAD CRANE TROLLEY IN THE MODE OF DAMPING UNCONTROLLED LOAD OSCILLATIONS

The paper deals with the modeling and optimization of the processes of movement and acceleration of a bridge crane trolley in the mode of damping uncontrolled oscillations of the load. For the dynamic system of a flat pendulum with vibration damping, which describes the oscillations of a bridge crane load on a flexible rope suspension in a separate vertical plane, it is proposed to use third-order time splines that model the motion and acceleration of the load suspension point in the horizontal direction of the trolley's movement. To determine the time dependence of the angle of deviation of the crane from the gravitational vertical, it is proposed to use the methods of classical calculus of variations (Euler-Poisson equation), which allow optimizing (minimizing) the value of this angle in the process of accelerating a trolley with a load suspended from the ropes of an overhead crane. An analytical solution to the problem of damping residual uncontrollable oscillations of the overhead crane load, which usually occur after full acceleration or braking of the load suspension point on the trolley, is obtained. To derive the dependencies, an analytical approach was used to calculate the value of the angle of deviation of the overhead crane's cargo rope from the gravitational vertical, depending on the acceleration and displacement of the load suspension point. The problem of loosening of a load moved by an overhead crane is considered and solved in a new way that allows to completely avoiding pendulum spatial oscillations of the load on a rope suspension. The mathematical apparatus of linear algebra (Kramer's rule, in particular) is used, which allows us to establish analytically the law of time motion of a rope with a load, the angle of deviation of which from the vertical takes minimum values in the process of acceleration of the cargo trolley.

MOTION LAWS DEVELOPMENT OF TROLLEY MOVEMENT AND TOWER CRANE SLEWING

The article presents an approach that allows to calculation optimal trajectory of load movement in the building yard. This trajectory provides avoiding obstacles in a way, that ensures the smoothness of the load movement. The essence of the developed approach is in multiple recalculations of the trajectory: the first step brings the shortest path from the initial point to the final point and the obstacle point is in the connection of two parts of the trajectory; the second stage provides changing the second part of the trajectory by a smooth (polynomial) law, that is connected with the first part at the angle 180 degrees; the third stage allows to add acceleration and deceleration modes of motion to the trajectory and reduces the load velocity when it goes near obstacle point. All of the calculations are carried out in an analytical way, and example of numerical calculations is presented in the article as well. In order to make the needed calculation for shifting and rotation of the smooth part of the trajectory (second stage of calculation) all the path was converted into discreet form. Mentioned operation of rotation was carried pot with a rotation matrix. In order to calculate discreet values of mechanisms' velocities the modified digital Savitzky-Golay filter was applied. The output results may be implemented by means of varied frequency drives of the mechanisms. The article ends with comparing of numerical indicators, which refer to the three stages. Among them are: gaps in the velocity of a mechanism during acceleration and deceleration, the gap in the velocity of a mechanism during obstacle avoidance, and the change in velocity sign of a mechanism. All of the indicators were calculated for both of the mechanisms: tower crane slewing and trolley movement. Comparison of the numerical indicators allowed us to conclude, that the final stage (calculations iteration) is the best among the comparable. However, it has some disadvantages, that need to be fixed in further investigations in this direction.

Neural network based adaptive control of gantry cranes

During the operation of large gantry cranes oscillations of flexible structures caused by the trolley movement lead to undesired wear of the construction and deteriorate the efficiency of the crane operation. Therefore, a neural network based adaptive control system for tracking control of the payload position and damping of oscillations is presented and validated in numerical simulations. By comparison to a previously derived nonlinear controller, it is shown that the proposed control law achieves good tracking and damping results with minimal a priori knowledge of the crane dynamics and without knowledge about specific plant parameters, therefore reducing the required modeling effort significantly.

Экспериментальные исследования колебаний трамвая «Витязь-М»

Objective: Based on experimental studies of vibrations of Vityaz-M tram car occurring at speeds of 50 km/h or more on track straight sections with P65 rails on reinforced-concrete sleepers, to evaluate the effect of transversal vibrations on traffic safety and passenger comfort. To show the inconsistency of existing regulatory documentation on the structure and maintenance of tram tracks and tram chassis with the development prospects. Methods: Experimental measurements of vibration accelerations of tram body and tram chassis, having different mileage, when moving along track experimental section. Measurement and analysis of geometric parameters of rail track experimental section and of trams. Results: Measurements of vibration accelerations occurring during tram motion with 20 to 50 km/h speeds were performed as well as geometric parameter analysis for rail track experimental section and rolling stock wheels’ profiles, participated in the tests, was pursued. During the races, vibration accelerations that occur during movement were measured in three directions — longitudinal, transversal and vertical. The appearance of transversal vibrations of tram body affecting passenger discomfort and traffic safety has been confirmed. The root mean-square values of the amplitudes of vibration accelerations towards three directions in acceleration gravity (g) fractions have been obtained in two variants — at trolley motion between joints and at joints. Vibration acceleration frequency analysis has confirmed a sharp increase in the amplitude of transversal vibrations at frequencies in the region of 1–2 Hz at a speed of 50 km/h for a tram with worn wheels. The compliance of rail track experimental section geometry with the accepted standards as well as the compliance of rolling stock wheels dimensions with constructive documentation are noted. Practical significance: The need for further comprehensive study of the interaction of track and rolling stock while high-speed tram introduction with the purpose to improve existing standards on the structure and maintenance of tram tracks and tram chassis.

A novel trajectory online planning and under-actuated control method on positioning and anti-swing for bridge cranes

The conventional bridge crane hoisting control method is limited by the complex factors of working conditions and generally adopts cumbersome off-line planning. In view of the problem of the inertia swing of the load caused by the trolley hauling the lifting rope during the transportation of the bridge crane, the trajectory off-line planning methods with the open-loop bring the control parameters to be complicated and tedious. A novel trajectory online planning and under-actuated control method on positioning and anti-swing for the bridge crane is proposed. According to the smooth positioning trajectory, the relationship among the motion parameters of the trolley, load swing angle, and other model parameters in the dynamic model are analyzed. With the dynamic coupling relationship between trolley motion and load swing, the function of anti-swing is designed online without changing the positioning performance. The trajectory online planning of the positioning and anti-swaying is accomplished. With the experimental and programming, the proposed method is compared with other different planning methods. The results show that this method can effectively realize the positioning and eliminating pendulum, and has the convenience of online adjusting parameters and fast response.

Adaptive Control of Two-Pendulum Suspension of Overhead Crane

When constructing the bridge crane control law, a two-pendulum model with a hook suspension, on which the transported load is suspended, and a load suspension is considered. This model more accurately describes the dynamics of cargo movement, which is especially critical in a number of crane operating modes, including cases when the mass-inertial parameters of the cargo are close to the hook. A mathematical model of the two-pendulum mechanical system of the crane suspension along one axis of its movement is described, taking into account the effect of friction forces when moving the crane trolley and wind disturbance acting on the transported cargo. Also, there is presented linearized model of hook movement with control action in the form of preset speed of crane trolley movement. The latter corresponds to the use of a servo motor or stepper motor to control the trolley. On the basis of the obtained linearized model, an adaptive control law is constructed using a scheme including an algorithm for current parametric identification, an implicit reference model, "simplified" adaptability conditions with direct tracking of hook movement (through it — cargo movement) by the properties of the assigned reference model. This control law allows you to build crane control under the current parametric uncertainty of the properties of the crane, the transported cargo and external disturbances (only approximate information about some parameters is assumed). It is shown that in the case when the natural frequency of the assigned reference model is less than that for the hook suspension, the proposed control law generates asymptotic movement of the hook (load) to the assigned point and damping of angular oscillations of the hook suspension and load suspension. For more efficient damping of angular oscillations in case of large values of load moment of inertia, it is proposed to supplement preset value of hook movement with damping movements based on angular movement of load suspension. Model examples supporting theoretical conclusions are given. It is shown that the proposed solution makes it possible to build a bridge crane control under the action of measurement noise and control signal delays.

Research on Hardware System Design Method of the Intelligent Vehicle Based on Dual Sensors

With the rapid development of modern society, the application of intelligent unmanned vehicles is becoming more and more popular. Based on the scene of unmanned vehicle patrol operation in an intelligent warehouse and simplifying it, this paper designs an image processing and perception of driving road conditions with ATM89C51 single-chip microcomputer as the core, camera, and infrared sensors to realize the detection of car trajectory. Two groups of four DC motors are set to drive, and the turning is carried out through the differential speed of the wheel motors on both sides. The turning radius and turning time are shortened through the independent control of the motors on both sides. The L298N full-bridge motor drive core is used to control the speed of the motor, to realize the accurate control of the trolley movement, and lay the foundation for the intelligent operation of the trolley in more scenarios. The accuracy of car navigation and motion control is improved through dual sensors.

Minimisation of the driving torque of the derricking mechanism of a tower crane during steady load hoisting

Efficient use of a tower crane often requires combining various operations, such as hoisting load and derricking. In the case when the load is hoisted at a steady speed, the problem of optimal control of the trolley movement mechanism arises, which goes beyond engineering calculations and is a scientific and applied problem. Its relevance is related to improving the controllability of crane mechanisms, increasing the capacity and reliability of the crane, and improving the energy efficiency of its drive mechanisms. These indicators are related to the choice of optimisation criteria. Thus, the purpose of the study is to optimise the starting mode of the derricking mechanism according to the criterion of the RMS value of the driving moment during a steady load hoisting. To achieve this goal, the following methods were applied: dynamics of machines and mechanisms, mathematical modelling, integral and differential calculus, and the ME-D-PSO method. For the boundary conditions, parameters are selected that eliminate load oscillations on the flexible suspension when the derricking mechanism slews to the steady-state driving mode. Based on the results of optimisation of the joint movement of mechanisms for derricking and load hoisting, graphical dependences of kinematic, dynamic, and energy characteristics of the start-up transition process are constructed and their analysis is carried out. The obtained dependences reveal the conditions for eliminating load oscillations on a flexible suspension during steady-state movement and reducing dynamic loads and energy losses during the start-up of the derricking mechanism. To implement the optimal start mode of the derricking mechanism during steady load hoisting, it is recommended to use optimal control of the drive mechanisms. The results obtained should be applied to the development of new and modernisation of existing motion control systems for tower crane mechanisms

The dynamic analysis of the joint trolley movement and hoisting mechanism in the tower crane

The task of this paper is to research the simultaneous use of trolley and hoisting mechanism by the tower crane with a beam jib. To conduct research, a dynamic model of joint movement of mechanisms has been developed, which takes into account the main movement of drive mechanisms and oscillating movement of the load on a flexible suspension and links of mechanisms with elastic properties. A mathematical model of the motion of mechanisms is constructed on the basis of a dynamic model with the help of Lagrange equations of the second kind. For a specific jib system of the tower crane, dynamic calculations were performed using the developed mathematical model. According to the results of the calculations, a dynamic analysis of the joint movement of trolley and hoisting mechanism was carried out. The analysis revealed significant dynamic and energy overloads of mechanisms during transients (start, braking) and the presence of high-frequency oscillations in the links with elastic properties and low-frequency oscillations of the load on a flexible suspension.
 To reduce the overload of crane mechanisms in the areas of transients and eliminate oscillations during steady traffic, it is recommended to optimize traffic modes and develop drive control systems to implement the desired traffic modes.

Trajectory Predictions with Details in a Robotic Twin-Crane System

Nowadays, more automated or robotic twin-crane systems (RTCSs) are employed in ports and factories to improve material handling efficiency. In a twin-crane system, cranes must travel with a minimum safety distance between them to prevent interference. The crane trajectory prediction is critical to interference handling and crane scheduling. Current trajectory predictions lack accuracy because many details are simplified. To enhance accuracy and lessen the trajectory prediction time, a trajectory prediction approach with details (crane acceleration/deceleration, different crane velocities when loading/unloading, and trolley movement) is proposed in this paper. Simulations on different details and their combinations are conducted on a container terminal case study. According to the simulation results, the accuracy of the trajectory prediction can be improved by 20%. The proposed trajectory prediction approach is helpful for building a digital twin of RTCSs and enhancing crane scheduling.

SWINGING OF THE LOAD ON THE TOWER CRANE AND PROBLEMS OF FIXING THE OSCILLATORY MOVEMENTS OF THE LOAD

The article considers the issues associated with the swinging of the load on the flexible suspension, the mechanical scheme of movement of trolley with load on the flexible suspension is represented, the processes start traveling mechanism of the trolley on a tower crane are investigated, the substantiation for the application of safety devices with the registration parameters fixed (register) load-swing is given, presented models of technical solutions to commit (register) load-swing.

Simulation of Crane Trolley Motion Control to Reduce Load Sway

the work aims to develop a method for controlling a crane trolley, providing a decrease in the swinging of the load on the rope at a given positioning accuracy and minimum time for moving the load.Computer simulation of the trolley controlled movement with a load on a rope was carried out within the "Universal Mechanism" software.The 2D computer model includes a trolley with a pulley, a rope with a hook, and a load. T-force represents the wind force effect.The control system (CS) contains three blocks that ensure the movement of the trolley with limited speed and acceleration, the positioning accuracy of the trolley, limiting the deviation and acceleration of a load. List of requirements for the crane CS comprises six issues.The simulation results illustrate the satisfactory performance of the proposed method. The swing angle and trolley positioning accuracy can be controlled within the acceptable range and the external wind disturbance on the load can be successfully suppressed. The optimal parameters of the proportional-differential corrective control, which ensure the minimum travel time of the trolley with limited oscillation of the load, have been determined. The optimal values of the control parameters depend on the inertial characteristics of the load. The maximum permissible values of speed, acceleration, and positioning errors of the trolley limit from above the optimal values of the control parameters.

Discrepancy-based control for positioning of large gantry crane

This paper is concerned with nonlinear control for positioning of large gantry cranes. An important structural dynamics problem of this type of cranes are flexible structural vibrations in the direction of trolley travel. They lead to faster wear of the crane construction and worsen the performance of the crane operation. Since they are mainly caused by movement of the trolley, they can be taken in consideration by redesign of the trolley motion control system. To design an appropriate control law, a generalized error measure, known as the discrepancy, is applied. Utilizing the associated stability with respect to two discrepancies, a nonlinear stabilizing control for large gantry cranes is obtained. The proposed control has been evaluated on a mathematical model and an experimental laboratory crane.

Jib Vibration and Payload Swing of Tower Cranes in the Case of Trolley Motion

Jib Vibration and Payload Swing of Tower Cranes in the Case of Trolley Motion

Dynamic simulation of a high altitude gantry crane with cable hoisting. Part one. 2D model

Introduction. Simulation of the 2D dynamic motion of a high altitude wide span gantry crane with a rope hoisting mechanism is addressed. Such large gantry cranes with a height of more than 50 meters, have been unstudied very well so far. A small swing angle of the payload, it's fast hoisting, and the fast motion of the trolley are critical for these cranes and, hence, they need to be analyzed in detail.
 Materials and methods. The generalized formulation of the two-dimensional crane dynamics is efficiently performed and simulated in Mathcad. This is a single mass model that has a non-elastic cable. The formulation is derived using the Lagrange method, and differential equations are correctly solved using the Runge-Kutta method in Mathcad. In this model the crane is fixed, and all the subsystems are considered as rigid bodies without any deflection in terms of the trolley and the payload.
 Results. The results are verified using MSC ADAMS (Academic) that indicates satisfactory convergence. The considerable influence of the payload oscillation on the trolley motion is visible in both Mathcad and ADAMS models. The implemented Mathcad code can be useful for students and researchers.
 Conclusions. The maximum speed of the trolley is 1.716 m/s to prevent the payload swinging angle from exceeding 0.5 deg. The calculated velocity of the trolley is reasonable for such a large crane if limitations like wind effects and resonance are ignored.

Design of Motion Control Software System of Geotextile Paving Trolley for Tunnel Construction

In tunnel waterproofing construction, the method of laying geotextile and waterproof board is generally used. Because the geotextile material is relatively soft, and it is not easy to shape, which brings great inconvenience to the work of construction personnel. Through the analysis of the tunnel waterproofing construction process, based on the tunnel construction geotextile paving trolley, the software system of the trolley motion control system is designed. This system includes the controller program design and the man-machine interface design, and finally cooperates with the hardware system. Debugging verified the system function and the reliability of the equipment.