Rotary Crane Research Articles

Load-Sway Control for Rotary Crane Considering Torsional Deformations of Vertical Jib

Large rotary cranes have a lattice structure tower boom which causes torsional deformation when transporting heavy loads. Therefore, it is necessary to design a controller that takes into account the torsion of the tower boom to control the load-sway and position of the jib. This study proposes a linear state-space model of rotary cranes that takes into account the torsion of the tower boom which stands vertically, and designs a controller using this model. Both simulation and experimental results are investigated to illustrate the superior performance of the controller designed in this study.

Time-Optimal Trajectory Generation of Rotary Cranes with Collision Avoidance

This paper presents a new three-dimensional trajectory generation method for a rotary crane using a simple dynamics model. The proposed trajectory achieves fast motion and suppresses load-sway with obstacle avoidance, which is generated by a combination of the A* algorithm and a time-optimization approach. The former is used to generate a shortest-distance path for a transported load considering obstacle avoidance. The time-optimization scheme is applied to the path generated by the A* algorithm under crane dynamics and load-sway constraints. The proposed trajectory is represented by a polynomial function to provide smooth and practical motion. Simulation results demonstrate the effectiveness on load-sway suppression and obstacle avoidance.

Vibration reduction of the rotary crane with flexible boom

Vibration reduction of the rotary crane with flexible boom

Nonlinear vibration suppression control of underactuated shipboard rotary cranes with spherical pendulum and persistent ship roll disturbances

Shipboard rotary cranes are widespread used in industrial fields to carry out large-scale cargoes under marine environment, which are a class of representative nonlinear systems. For crane systems, there exist unactuated state variables (e.g., payload swing angles), which hence make them typically underactuated systems, whose degrees of freedom (DOFs) are more than the number of control inputs. Besides, due to the complexity disturbances of the marine environment, there are always inaccuracies in the three-dimensional (3D) dynamics model of shipboard rotary cranes, such as ocean waves, wind waves, ocean currents and so on, which make the control methods hard to achieve the perfect control effect. Most of the existing methods are built on the basis of simplified linear model, which often require precise model parameters or velocity signals. In order to solve the control problems caused by the above uncertainties, this paper proposes two nonlinear anti-swing control methods. First, considering the uncertain parameters, an adaptive controller is designed, which can achieve the control effect of suppressing swing when the model has unknown parameters. Second, considering the unmeasurable velocity signals, an output feedback controller is designed, which can achieve the control effect to suppress the swing angle with no need of velocity signals. On the basis of the above two control methods, we design corresponding different energy storage functions including kinetic energy and potential energy, respectively. Specifically, this paper has achieved an excellent effect of restraining swing without any linear approximation of the dynamic model. Lyapunov theorem and LaSalle invariance principle are utilized to further prove the asymptotic stability of the closed-loop system. Finally, experiments are implemented to further demonstrate the effectiveness of the proposed control methods.

Data-driven robust tracking control of underactuated mechanical systems using identified flat output and active disturbance rejection control

This paper presents a data-driven control design framework to achieve robust tracking without exploiting mathematical model of nonlinear underactuated mechanical systems (UMS). The method leverages differential flatness property of linearised systems, online estimation and compensation of disturbances by active disturbance rejection control. The differentially flat output is derived directly from measured data with unknown dynamics and parameters by the flat output identification algorithm. A reduced nominal model of UMS is proposed to simplify the process of finding flat output and trajectory planning. Technique of sparse regression is applied to identify relationships between flat output and system states, which reduce the order of the well-known extended state observer (ESO) and thereby make the ESO more effective for trajectory planning and tracking in terms of the flat output. The proposed control is validated by experimental studies of a rotary crane system in which a rest-to-rest tracking control is implemented.

Asymmetric Input-Output Constraint Control of a Flexible Variable-Length Rotary Crane Arm.

This article demonstrates the realization of angle tracking and deformation suppression by developing two boundary controllers for a flexible variable-length rotary crane arm with extraneous disturbances and asymmetric input-output constraints. The dynamic model description of this kind of crane arm system is several partial differential equations integrated into few ordinary differential equations. The S-curve acceleration and deceleration scheme is utilized to adjust the elongation rate of the arm. A kind of novel observer is put forward to tackle unknown extraneous disturbances. Auxiliary systems and barrier Lyapunov functions are introduced to meet the asymmetric input-output constraints. With the help of Lyapunov's theory, the global exponential stability and uniform boundedness are analyzed. The numerical simulations are finally provided to illuminate its availability of the designed control schemes.

Modelling and control of a knuckle boom crane

ABSTRACT Depending on their dynamic properties, cranes can be classified as gantry cranes and rotary cranes. In this paper, we will focus on the so called ‘knuckle boom’ cranes which are among the most common types of rotary cranes. A first result of this paper is to present a complete mathematical model for this kind of crane where it is possible to control the three rotations of the crane and the cable length. On the basis of this model, we propose a nonlinear control law based on energy considerations which is able to perform position control of the crane while damping the oscillations of the load. The corresponding stability and convergence analysis is carefully proved using the LaSalle's invariance principle. The effectiveness of the proposed control approach has been tested in simulation with realistic physical parameters and in the presence of model mismatch.

Nonlinear-adaptive-based swing reduction control for rotary cranes with double-pendulum effect considering uncertain parameters and external disturbances

Achieving both boom positioning and swing reduction becomes more difficult when rotary cranes display double-pendulum characteristic in dynamics. Moreover, in actual application, the model uncertainties and external disturbances always affect the control performance. To solve these problems, an adaptive nonlinear control method is designed. Through a large number of strict simulation verification of the above control methods, the following results can be obtained: Aiming at the research problems of model uncertainty and the existence of external disturbances, it reflects excellent control performance and strong robustness. Furthermore, the above results show that the proposed control method not only has important theoretical value, but also has practical engineering significance. Finally, the paper conducts follow-up research from the following directions: On the one hand, Lyapunov technology is used to design the controller; on the other hand, LaSalle's invariance theorem is used to analyze the stability of the closed-loop system.

Active disturbance rejection control of nonlinear SISO Lagrangian systems via endogenous injections and exogenous feedback for trajectory tracking

This article deals with a linear classical approach for the robust output reference trajectory tracking control of nonlinear SISO Lagrangian systems with a controllable (flat) tangent linearization around an operating equilibrium point. An endogenous injections and exogenous feedback (EIEF) approach is proposed, which is naturally equivalent to the generalized proportional integral control method and to a robust classical compensation network. It is shown that the EIEF controller is also equivalent, within a frequency domain setting demanding respect for the separation principle, to the reduced order observer based active disturbance rejection control approach. The proposed linear control approach is robust with respect to total disturbances and, thus, it is effective for the linear control of the nonlinear Lagrangian system. An illustrative nonlinear rotary crane Lagrangian system example, which is non-feedback linearizable, is presented along with digital computer simulations.

Boom motion trajectory generation approach for load sway rejection in rotary cranes considering double-pendulum effect

In the control research on the rotary crane systems with double-pendulum effect, a motion trajectory with both simple structure and excellent robust performance is proposed to achieve the positioning of the boom and the suppression of the load sway. The presented trajectory consists of an anti-swing component and a boom positioning component, where the first part is used to achieve the sway angle elimination without affecting boom positioning; the second one is used to move the boom to the desired location precisely. The Lyapunov technique, LaSalle’s invariance theorem, and Barbalat’s lemma are used to prove the excellent performance of the method. Eventually, the effectiveness of the proposed method was verified through a large amount of simulation data analysis.

The dynamic analysis of load motion during the interaction of wind pressure

This work presents the analysis of the load motion during the interaction of wind pressure. The load was treated as a rigid body, and the rope system model as a non-deformed. The influence of effective area of wind pressure on load motion was considered. The theoretical model of load motion was presented, which may be an universal approach for transporting machines equipped with a rope-lifting system. To define the orientation of the movable Cartesian coordinate system related to the load, Bryant angles were used. An algorithm and computational program were developed to allow for analysis of dynamic phenomena. The initial problem was solved with the use of the ode45 calculation procedure in the Matlab software on the basis of the Runge–Kutta 4th Order Method. The obtained results were verified with the experimental ones achieved in the wind tunnel and Tracker program. Numerical calculations using commercial software SolidWorks were also presented. In the experiment, the spatial motion of the load was analysed. Experimental tests were carried out for gust of wind and constant temperature and humidity. In addition, the paper presents the application of the proposed method for a load carried by a rotary crane. After taking into account the control functions resulting from the nature of the work of any machine, the formulated model can be a full description of the carried load motion taking into account external forces.

Vibration Control of a Rotary Crane by Elimination of the Natural Frequency Component

Vibration Control of a Rotary Crane by Elimination of the Natural Frequency Component

Identification of differentially flat output of underactuated dynamic systems

This paper presents a data-driven algorithm for identification of locally differentially flat output from system output measurements. No detailed mathematical model of the system is needed. Trial output is written as a linear combination of measured outputs. An optimal linear combination is identified so that the trial output achieves the highest relative degree. When the relative degree is equal to the order of the system, the output is flat. The identification is done in the frequency domain by taking advantage of the asymptotic behaviour of transfer functions of linear systems. We have also developed data handling strategies to obtain the best estimate of the relative degree in the presence of measurement noise, high-frequency dynamics and Nyquist digitisation effect. The proposed algorithm is validated by numerical examples and an experimental study of a rotary crane system.

Nonlinear Motion Control of Complicated Dual Rotary Crane Systems Without Velocity Feedback: Design, Analysis, and Hardware Experiments

As a class of underactuated systems, cooperative dual rotary crane systems (DRCSs) are widely used to complete the task of large payload transportation in complex environments, since the working capacity of single cranes is quite limited. However, the control issues of DRCS fail to receive enough attention at present. Compared with single cranes, DRCSs contain more state variables, geometric constraints, and coupling relationships. Therefore, the complex kinematic and dynamic characteristics make controller design/stability analysis very challenging for DRCS. In order to solve these problems, based on the dynamic model of DRCS established by Lagrange’s method, an output feedback control method with consideration for actuator constraints is designed to realize accurate dual boom positioning and rapid elimination of payload swings. The stability of the equilibrium point for the closed-loop system is analyzed by using Lyapunov techniques and LaSalle’s invariance principle. To the best of our knowledge, this article yields the first solution for effective control of DRCS, which needs no velocity feedback, respects the actuator constraints, and is designed and analyzed without linearizing the complicated nonlinear dynamic equations. Finally, a series of hardware experiments on a self-built experimental platform is carried out to illustrate the effectiveness of the proposed controller. Note to Practitioners —This article is motivated by the control problem of dual rotary boom crane systems. In order to meet industrial requirements, the masses and volumes of to-be-hoisted cargoes are larger than before, and consequently, dual-crane systems are more frequently needed to fulfill transportation tasks. For such systems, although they improve the load capacity, greater challenges are caused when eliminating cargo swings in the transportation process. To the best of our knowledge, current control methods are mainly designed based on linearized/reduced models, whose performance may be not satisfactory when swing angles are large. Moreover, most methods use velocity signals with unexpected noises and ignore the constraints of actuators’ amplitudes, which may not be feasible in practical applications. To solve these problems, this article presents an output feedback controller, which can simultaneously solve the problems of saturation constraints and velocity signal unavailability. The proposed controller can guarantee accurate boom positioning and cargo swing elimination with guaranteed theoretical proof. Furthermore, the control performance is verified experimentally on a self-built testbed. In future efforts, we intend to apply the presented control method to industrial applications.

Energy-shaping-based nonlinear controller design for rotary cranes with double-pendulum effect considering actuator saturation

Dynamic performance analysis and controller design become more difficult when the load sway in rotary cranes exhibits double-pendulum characteristics. Furthermore, uncertain parameters and external disturbances in the crane system make it difficult for traditional methods to obtain satisfactory control performance. In addition, in an actual crane system, because of physical constraints, the output torque of the motors cannot be infinite. Therefore, the motor torque calculated by existing methods may exceed the maximum value, and actuator saturation will occur, which will affect the control performance. For this purpose, an energy-shaping-based nonlinear controller is presented after simplifying the original crane model. Stability analysis is carried out using the Lyapunov technique and LaSalle's invariance theorem. Numerical simulations validate that the proposed method can provide a robust control performance superior to that of traditional controllers.

Tracking and load sway reduction for double‐pendulum rotary cranes using adaptive nonlinear control approach

SummaryBecause of the existence of rotational boom motion, the load sway characteristics is more complex. In particular, when the sway presents double‐pendulum phenomenon, the design of the controller is more challenging. Furthermore, the uncertain parameters and external disturbances in crane system make it difficult for traditional control methods to obtain satisfactory control performance. Hence, this paper presents an adaptive nonlinear controller based on the dynamic model of double‐pendulum rotary crane. Unlike a traditional method, the proposed one does not need to linearize the crane system for controller design; therefore, the control performance can be guaranteed even if the system states are far away from the equilibrium point. By using Lyapunov technique and LaSalle's invariance theorem, it is strictly proved that the whole control system is asymptotically stable at the equilibrium point. The effectiveness of the presented controller is demonstrated via comparative simulations.

Impact of Wind on the Movement of the Load Carried by Rotary Crane

This paper considers the coupled kinematic and dynamic models of a mobile crane. A full description of boom and load movement has been provided as a response of the system to the influence of kinematic forces. The linear system model was treated as rigid, and the carried load as a nondeformed static body. To describe the position of said load, Bryant angles were used. The dynamic model includes the impact of external forces (wind pressure) while load carrying and positioning. Algorithm and calculation software were developed to enable dynamic phenomena analysis during both a work cycle and free movement of said load. The initial problem was solved by means of the ode45 calculation procedure in the Matlab software based on the Runge–Kutta 4th Order Method. The work presents exemplary results of load movement simulation with respect to various wind velocities, selected on the basis of guidelines from Poland’s standards regarding safe operation of mechanical equipment.

Inverse Kinematics of 2-DOF Rotary Crane Fixed on Two Barges for Collaborative Tasks During Offshore Installation

Inverse Kinematics of 2-DOF Rotary Crane Fixed on Two Barges for Collaborative Tasks During Offshore Installation

A rotary tower crane system: an appealing problem in nonholonomic mechanics

ABSTRACT Cranes system is widely used to transport heavy loads and hazardous materials in shipyards, factories, nuclear installations and high-building construction and plays an important role in the production process and serves to transfer loads from one place to another. Cranes are the best way of providing a heavy lifting facility covering virtually the whole area of the industry. The equations of motion of a rotary tower crane are highly non-linear, and rolling without slipping condition of the trolley on the jib plane can only be expressed by nonholonomic constraint equations. In this paper, a geometrical theory of general nonholonomic constrained systems on fibred manifolds and their jet prolongations, based on so-called Chetaev-type constraint forces, was applied to the above-mentioned mechanical problem. The dynamical model is preserved in simulations in its original non-linear form without any simplification. The results of numerical solutions of constrained equations of motion, derived within the theory, open the possibility of direct application of the theory to practical situations.

Adaptive Anti-Swing and Positioning Control for 4-DOF Rotary Cranes Subject to Uncertain/Unknown Parameters With Hardware Experiments

Among various large-scale mechanical equipments, a rotary crane is one of the most practical hoisting machineries utilized in factories and docks. However, the inaccurate measurement of friction coefficients and the requirement of accurate gravity-related compensation may inevitably increase the difficulty for controlling such systems. For most existing control methods, the exact model knowledge is required; otherwise, positioning errors would unavoidably appear, which brings many limitations for their practical applications. To deal with these problems, in this paper, a novel adaptive control approach is suggested, in which a novel update law is designed to achieve accurate identifications of unknown parameters as well as exact compensation of the gravity-related lumped term. Moreover, the payload can be transported to its specified location precisely via the boom’s rotation with effective payload swing suppression. Specifically, without linearizing the nonlinear dynamic model of the rotary crane system, the state variables are ensured to be asymptotically convergent to the equilibrium point, which is proven strictly in theory by utilizing Lyapunov techniques and LaSalle’s invariance principle. Finally, experimental results indicate the effectiveness and practicability of the proposed approach.