Crane Control Research Articles

Discrete-time flatness-based control of a gantry crane

This article addresses the design of a discrete-time flatness-based tracking control for a gantry crane and demonstrates the practical applicability of the approach by measurement results. The required sampled-data model is derived by an Euler-discretization with a prior state transformation in such a way that the flatness of the continuous-time system is preserved. Like in the continuous-time case, the flatness-based controller design is performed in two steps. First, the sampled-data system is exactly linearized by a discrete-time quasi-static state feedback. Subsequently, a further feedback enforces a stable linear tracking error dynamics. To underline its practical relevance, the performance of the novel discrete-time tracking control is compared to the classical continuous-time approach by measurement results from a laboratory setup. In particular, it turns out that the discrete-time controller is significantly more robust with respect to large sampling times. Moreover, it is shown how the discrete-time approach facilitates the design of optimal reference trajectories, and further measurement results are presented.

Wireless Control Modelling for Overhead Crane

Radio frequency (RF) remote controllers are widely used in manufacturing, construction, transportation, and many other industrial applications. Cranes, drills, and miners, among others, are commonly equipped with RF remotes. Installation wired communication takes a long time to set up the connection as compared to the wireless connection. The installation becomes very lengthy and complex if we want to get connected with each router. For the same reason, for a system expansion to add more device(s), the re-routing process to connect this new device(s) to the network can be avoided. Instead, with the wireless connection, we don’t have to perform all the setup again. The network can be accessed with the authorized passcode. Radio-controlled devices are ubiquitous in all sorts of industries. In fact, many cranes are now being equipped with radio-controlled technology, which is revolutionizing the way crews move materials around a warehouse or job site. In the steel manufacturing industries, the wireless crane control has proven to assure. more advantage compared to the disadvantage. Through the surveillance and monitoring of wireless remote control for crane that done at AJSB, Prai, Malaysia.

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.

Novel Concept for Electro-Hydrostatic Actuators for Motion Control of Hydraulic Manipulators

Self-contained hydraulic cylinders have gained popularity in the recent years but have not been implemented for high power articulated hydraulic manipulators. This paper presents a novel concept for an electro-hydrostatic actuator applicable to large hydraulic manipulators. The actuator is designed and analyzed to comply with requirements such as load holding, overload handling, and differential flow compensation. The system is analyzed during four quadrant operation to investigate energy efficiency and regenerative capabilities. Numerical simulation is carried out using path control and 2DOF anti-swing of a hydraulic crane as a load case to illustrate a real world scenario. A comparison with traditional valve-controlled actuators is conducted, showing significantly improved efficiency and with similar dynamic response, as well as the possibility for regenerating energy.

Payload motion control for a varying length flexible gantry crane

Cranes play a very important role in transporting heavy loads in various industries. However, because of its natural swinging characteristics, the control of crane needs to be considered carefully. This paper presents a control approach to a flexible cable crane system in consideration of both rope length varying and system constraints. At first, from Hamilton's extended principle the equations of motion that characterized coupled transverse-transverse motions with varying rope length of the gantry are obtained. The equations of motion consist of a system of partial differential equations. Then, a barrier Lyapunov function is used to derive the control located at the trolley end that can precisely position the gantry payload and minimize vibrations. The designed control is verified through extensive experimental studies.

An EEG Study of the Brain Workload Under Virtual Reality and Real Environment

Cranes are used extensively in many industries throughout the world, in a wide array of environments, including some that are hazardous to humans. The vast majority of cranes are directly controlled by human operators. In some cases, it is necessary to remove the human operator from hazardous operating conditions, creating a crane that must be remotely operated. This, however, introduces additional challenges for the operator, who must now control the oscillatory payload while suffering from decreased perception of the environment and the potential time delays caused by remote operation. This paper presents two studies of crane operator performance with varying time delays. The results show that the type of crane control and duration of the communication time delay directly influence task completion time and difficulty. Input shaping control is shown to improve completion times and lower operator effort.

Precision-positioning adaptive controller for swing elimination in three-dimensional overhead cranes with distributed mass beams

As a type of dispensable transport tool, overhead cranes are extensively applied in large industrial sites to transport containers and goods due to their extraordinary convenience and efficiency. However, various transport requirements and working environments may cause some adverse effects for overhead crane control. In particular, in some transport tasks, distributed-mass beams (DMB) are required to be transported smoothly to a specific position. Hence, most existing controllers designed for crane systems with point-mass payload (PMP) cannot meet the control requirements. For example, controllers designed for crane systems with PMP do not consider the moment of inertia of DMB, thus, the residual payload swing caused by the moment of inertia cannot be completely suppressed, which may cause safety risks. Additionally, due to various working environments, inaccurate estimation of frictions can result in errors in positioning. To solve the above issues, this paper conducts the dynamic analysis of three-dimensional (3-D) overhead crane systems with DMB and designs an improved adaptive controller which can provide favorable control for state variables. In particular, the proposed update laws can compensate for the uncertainties of crane systems. Based on a tracking trajectory, the trolley and guide rail can both reach the preset position, and the swing angles are also well eliminated throughout the transport process. The stability of the control system is proven theoretically, and the performance of the proposed controller is verified by comparative experiments.

Hairpin RNA genetic algorithm based ANFIS for modeling overhead cranes

Obtaining an accurate mathematical model is an important subject to design an overhead crane control system. However, there are some deviations between an existing model and a physical system due to its nonlinearity and complexity characteristics. Motivated by this fact, an adaptive network-based fuzzy inference system (ANFIS) modeling method is proposed for obtaining high precision models. One of the challenges in ANFIS modeling is how to effectively optimize the premise and consequent parameters. To solve this problem, we propose the RNA genetic algorithm with hairpin genetic operators (hRNA-GA). In hRNA-GA, inspired by the hairpin structure in RNA molecules, we design the hairpin crossover operator and the hairpin mutation operator to maintain the population diversity and avoid the premature convergence. Numerical experiments have been conducted on some benchmark functions. The results indicate that hRNA-GA has better search ability with respect to quality and stability of solutions. Finally, hRNA-GA is applied to find the optimal parameters of ANFISs for modeling an actual overhead crane system and the satisfactory results are reached.

Passivity-based coupling control for underactuated three-dimensional overhead cranes

This paper develops a novel Lyapunov function candidate for control of the three-dimensional (3-D) overhead crane, which yields a nonlinear controller to inject active damping. Different from the existing passivity-based controls that employ either the angular displacement or its integral as passive elements, the proposed controller incorporates both of them in a new coupled-dissipation signal, thus significantly enhancing the closed-loop passivity. Owing to the improved passivity, the proposed controller ensures the effective suppression of payload oscillations and robustness. Moreover, the control design is extended with the hyperbolic tangent function to prevent overdriving the trolley. The asymptotic stability is guaranteed by LaSalle’s invariance principle. The transit performance of the closed-loop system, including robustness, is validated by numerical simulations.

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.

Anti sway tuned control of gantry cranes

Load swaying is one of the most frequently occurring problems at production sites. The purpose of this work is to create a control system for the movement of an overhead crane with an anti-sway function. The Particle Swarm Optimization method has been used to find the controller coefficients. The crane movement with the anti-sway function should be implemented using a PLC (programmable logic controller) and have a high speed of operation. The frequency converter controls the speed of the drive that moves the crane. The main advantage of the system is its simplicity and low cost combined with the low swaying of the load. The oscillation amplitude with an angular speed regulator is two to three times less in comparison with the control system without the angular speed regulator. The presence of an angular speed regulator minimizes the impact of the load weight and the rope length. The efficiency of the simulator program for calculating angular speed has been tested and confirmed. Verification of the created mathematical model of the crane with experimental installation has been made.Article HighlightsAn efficient and low-cost anti-sway system for overhead cranes has been developed. The efficiency of the system was tested experimentally, the dependencies of the influence of factors on the sway angle were obtained. The selection of the regulator coefficients is implemented using the particle swarm optimization method coded in C++, which provides high-speed performance and the ability to integrate the algorithm into the PLC of the overhead crane control system.

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.

Suppression of Residual Vibration in Nonlinear Systems With Temporal Variation and Uncertainty in Parameters by Elimination of the Natural Frequency Component

Abstract A systematic approach is developed for determining a control input for the point-to-point control of an overhead crane that exhibits temporal variation of rope length in addition to damping and nonlinearity, without inducing residual vibration. Complete suppression of the residual vibration is achieved by eliminating the natural frequency component of the cargo from the apparent external force, which is defined to include the effects of damping, nonlinearity, and parameter variation. Furthermore, an effective technique previously proposed by the authors for improving robustness to the modeling error of the natural frequency is extended. Numerical simulation results show that, even when cargo is hoisted up or down during operation, the proposed method realizes accurate positioning of the cargo without inducing residual vibration and sufficiently improves robustness. To the best of our knowledge, this is the first frequency-domain robust open-loop control strategy that ensures a theoretical zero amplitude for residual vibration in the absence of modeling error in nonlinear crane hoisting operation. The developed method is not only a contribution to the realization of low-cost and efficient crane hoisting operation, but is also applicable to the control of other nonlinear damped systems that include time-varying parameters.

Passivity-based adaptive trajectory control of an underactuated 3-DOF overhead crane

This paper presents a robust passivity-based adaptive control method for payload trajectory tracking of a three degree-of-freedom overhead crane with a varying-length rigid hoist cable. A reformulation of the overhead crane’s equations of motion is used and an adaptive control law is developed to ensure the system has an output strictly passive (OSP) input–output mapping. The Passivity Theorem is used to prove that the closed-loop system is input–output stable when an OSP negative feedback controller is implemented. Convergence and boundedness of the payload trajectory tracking error is proven with two candidate OSP feedback controllers, including a constant gain and a strictly positive real (SPR) controller. Numerical simulations and experiments are performed with the proposed control method and two state-of-the-art control laws from the literature. The results demonstrate the practicality of the proposed control method and the improved performance of the proposed SPR controller in the experiments compared to the controllers from the literature.

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.

Load Position Detection of Container Crane Using Camera

In this study, the authors proposed an image processing algorithm to detect (measure) the rope length of container crane (distance from camera system to container spreader) and sway angle of the spearder (container). This measurement will be the main input to design the anti-sway control system for container cranes. The image processing algorithm includes the main steps: converting from BGR color space to HSV color space, then, binary image is used to extract the marker area. Next, the Canny boundary detection technique is applied to determine the boundary of the markers in the container spreader. The center location of each marker is determined and used to calculate the distance from the camera system to the container spreader is calculated. The rope length accuracy by the image processing algorithm is 99,79%. It is satisfied for crane control purpose.

Anti-sway control of offshore crane on surface vessel using global sliding mode control

ABSTRACT In this paper, the global sliding mode control technique is designed for anti-sway control of offshore crane mounted on surface vessel. The offshore cranes are responsible for moving containers from mega container ships to a smaller vessel. In this regard, after introducing the dynamics of the crane mounted on the surface vessel, the sliding surfaces and control laws are designed to maintain the stability of the system against external disturbances such as sea waves and wind induced movements. Furthermore, using the Lyapunov’s stability analysis, it is proven that the position/ velocity errors are converged to the origin. Finally, to determine the effectiveness of the proposed method, the simulation results of the global sliding mode control technique are compared to those of the continuous integral sliding mode control and proportional–integral–derivative approaches. The development of this procedure due to its high productivity and economic feasibility can be used as a new tool in the modern maritime industry.

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.

Adaptive Control Design for Underactuated Cranes With Guaranteed Transient Performance: Theoretical Design and Experimental Verification

For antiswing control of underactuated cranes, how to guarantee the converging speed of cranes through control design is essential but still remains unsolved. In this article, the adaptive antiswing control for underactuated gantry cranes with guaranteed transient performance under unmodeled dynamics and external disturbances is investigated. To sovle this problem, a set of filters are proposed to make the backstepping technique applicable for the control of crane systems. Then through variable transformation the position error and swing angel could be guaranteed converging to the origin with a given exponential speed. Hardware experiments are conducted to show that the proposed scheme achieves better control performance over existing methods, and it is illustrated that the proposed control scheme possesses strong robustness to unmodeled uncertainties and external disturbances.

Study of anti-swing control of ship cranes based on time delay feedback

2 tons 3 meters ship crane as the research object, establish the complete mathematical model of ship crane, and design the time-delay feedback control algorithm to eliminate payload swing on the basis of the built mathematical model. First, a high-precision potentiometer is used to measure the in-plane and out-of-plane oscillation of the payload. Measuring devices for the rotary angle and variation amplitude angle are created, and the anti-swing control hardware system is built by the sensing unit and the High-Speed Data Acquisition hardware system. Secondly, the control software on the VB platform is developed using the time-delay feedback algorithm. Experimentally study the effect of time-delayed feedback controller on payload swing elimination, and use induction method to get the optimal control parameters of the time-delayed feedback control algorithm. At last, the AMEsim-ADAMS co-simulation platform was built to evaluate the payload sway of the ship crane under simulated working conditions. The results show that: the hardware and software systems for anti-swing control built-in the paper can give the real-time and the exact payload swing angles. The method of adding time-delay feedback control signal to the slewing operation signal can achieve better anti-swing effects than the others. At the same time, the delayed feedback control algorithm still has a nice control effect in the case of virtual ship deck motion.