Payload Swing Angle Research Articles

Discrete adaptive sliding mode controller design for overhead cranes considering measurement noise and external disturbances

AbstractResearch on the motion control of overhead cranes, constrained by underactuated characteristics, helps improve the efficiency of payload transportation. Most studies require all system state variables (trolley displacement, payload swing angle, and their velocities). In practice, sensors measure and transmit these variables, but noise affects their accuracy, reducing control performance. Additionally, uncertainties in crane parameters, unmodeled friction, and unknown disturbances threaten the system's stability. Traditional methods struggle to address these issues effectively. To address these challenges, this article proposes an adaptive discrete sliding mode control (DSMC) method with a Kalman filter. By extending the state system and considering disturbances as new variables, the Kalman filter effectively eliminates signal noise, accurately estimates disturbances, and estimates system states simultaneously. The proposed method incorporates disturbance compensators into the adaptive DSMC, utilizing exponential terms to suppress oscillations caused by excessively high or low control gains, thus increasing control speed. Experimental comparisons demonstrate the superiority and robustness of the proposed control method under various disturbance conditions.

Adaptive sliding mode anti-swing control of 4-DOF tower crane based on a nonlinear disturbance observer

Tower cranes are widely applied in outdoor environments with inevitable external disturbances, which can reduce transportation efficiency and safety. To improve the transient control performance of the tower crane when transporting goods and to guarantee good robustness, this paper designs an adaptive sliding mode Anti-swing control method based on a nonlinear disturbance observer. Firstly, a 4-DOF tower crane error dynamics model considering external disturbances and air friction is established, and then, a nonlinear disturbance observer is designed to estimate the aggregate disturbance. Further, a disturbance effect indicator (DEI) is set to judge the advantages and disadvantages of the disturbance effect on the tower crane system from a new perspective. Finally, beneficial disturbance effects are organically combined with a sliding mode control method possessing an adaptive mechanism to eliminate payload swing by introducing favorable interference. Using Lyapunov stability analysis in conjunction with the LaSalle invariance principle, the closed-loop system is shown to be asymptotically stable. Simulation results show that the controller proposed in this paper achieves accurate positioning by driving the trolley and the jib, and at the same time, can keep the payload swing angle slight during the working process and eliminate the payload swing angle after accurate positioning. Moreover, it is also robust in the face of external disturbances and system parameter variations.

An enhanced coupling nonlinear control for quadrotor with suspended double‐pendulum payload

AbstractIn the field of logistics transportation, unmanned aerial vehicles are commonly utilized for cargo transport in a suspended manner, and the suspended payloads will exhibit the double‐pendulum dynamic characteristics (dPDC). However, due to the underactuation and load‐swing problems caused by the dPDC, it is challenging to design controllers for a quadrotor with a suspended double‐pendulum type payload. Existing related studies simplify the dPDC to a single‐pendulum dynamic characteristic, which results in degraded transient performance. To overcome the issue, this article presents a novel controller approach that considers the real dynamic characteristics, that is, dPDC. The proposed approach tackles the quadrotor position control and anti‐swing problem in two steps. First, a composite signal incorporating both the quadrotor position and the payload swing angles is introduced to restrain the payload swing. Second, a nonlinear controller based on the energy analysis method is proposed to overcome the coupling between rotation and translation, which addresses the underactuation problem. Theoretical analysis confirms the asymptotic stability of the system under this control strategy. Numerical and experimental results are provided to demonstrate the effectiveness of the proposed controller.

Research on anti-swing control strategies for three-dimensional overhead cranes with non-stationary enhanced swing angle suppression

In this paper, a non-stationary enhanced swing angle suppression control strategy is proposed to address the issue of excessive swinging angles during the transportation process of a three-dimensional overhead crane. Firstly, in response to the substantial non-stationary initial swing angle resulting from the abrupt increase in driving force during the startup of the overhead crane, we have devised a time-varying damping resistance model. This model is specifically designed to curtail the rapid force surge, subsequently diminishing the swing angle of the payload. Secondly, during the transport phase of the overhead crane, we have established an augmented coupling signal between the displacement tracking error and the payload swing angle tracking error. Drawing upon the principles of energy dissipation, we have devised a nonlinear sway controller. Next, the closed-loop stability of the control system is validated through the use of Lyapunov’s method and the LaSalle invariance principle. Finally, the proposed control strategy’s effectiveness has been substantiated through simulation analysis and physical experiments. This approach not only proves capable of effectively suppressing excessive payload swing angles during the transportation process of the overhead crane but also facilitates the rapid and precise positioning of the payload. This significantly enhances the efficiency of the overhead crane’s transport operations.

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.

Active damping methods to suppress the payload swing by a 3‐degree of freedom cable‐driven parallel robot

AbstractMarine cranes play an important role in many hoisting scenes. However, due to the ship motion excitation and crane operation, the payload swing is unavoidable, hence putting the operators in danger. Thus, this paper proposes two active damping methods to suppress the payload swing by a 3‐DOF cable‐driven parallel robot (CDPR). First, the structure of the 3‐DOF CDPR is briefly introduced. Then, the dynamic model of the system is modeled as a constrained spherical pendulum with moving base excitations. Meanwhile, inspired by the air damping phenomenon, two active damping methods are presented to damp the payload swing naturally and smoothly. Furthermore, the payload swing under ship motion excitation and external hitting disturbances is analyzed, the influence mechanism of system damping parameters on the payload anti‐swing is discussed, and the robustness of the proposed damping methods is verified. By theoretical analysis and numerical simulations, some interesting discoveries are revealed: (1) the proposed damping methods can effectively suppress the big offset of payload swing angle inducing by external hitting disturbance, but the system might reach a dynamic equilibrium with a tilting hoist cable; (2) the phenomenon of “off‐center spherical pendulation” might be induced by improper setting of the damping parameters.

Dynamic modeling and control of hydraulic driven payload anti-swing system for shipborne cranes

Shipborne cranes are widely used in marine engineering and are employed in more diversified working scenes. However, due to the extensive swing range of ships, it is impossible to locate the payload accurately. A constant tension control method of payload anti-swing is proposed based on the principle of linear velocity feedback. This paper establishes a dynamic model of the payload anti-swing system driven by hydraulic motors. The characteristics of the payload swing and the cable tension are obtained through the dynamic simulation. The simulation and experimental results show that the constant tension control method significantly suppresses the shipborne crane’s payload swing, and the payload anti-swing effect reaches 73% and 85.6%. It is also found that the payload swings asymmetrically under external excitation. In addition, the effects of payload asymmetric swing on cable tension, payload swing angle, and the hydraulic pump output oil pressure are studied by a payload asymmetric swing experiment, and the results show that the proposed method also has a good suppression effect on the asymmetric payload swing.

Inverse motion planning method for overhead crane systems with state constraints

AbstractThe trajectory planning problem with state constraints of overhead crane systems is considered in this paper. A new method, that is, an inverse motion planning method, is proposed. On this basis, a new trajectory planner is designed. The payload swing angle trajectory is designed first, and then by substituting it into the dynamic equations, the trolley trajectory is derived. For any transportation tasks, the adjustable parameter of the planner is computed by solving the state constraints such that the system states; that is, the trolley acceleration, trolley speed, and payload swing angle will not exceed their predefined constraints. Several experimental tests are conducted to verify the swing elimination performance of the proposed method.

Adaptive Coupling Anti-Swing Tracking Control of Underactuated Dual Boom Crane Systems

Underactuated dual boom crane (DBC) systems exhibit complicated nonlinearity and strong coupling due to the lack of independent actuators. Moreover, plant parameters may change in different transportation tasks and are difficult to be measured accurately, which leads to inaccurate gravity (torque) compensation and further brings positioning errors. Hence, most existing controllers based on exact model knowledge cannot ensure satisfactory control performance <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">any longer</i> . In order to handle the above issues, this article designs an adaptive sliding mode tracking controller for DBC systems based on the original complicated nonlinear dynamics <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">without</i> any linearization/simplification operations, which is the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">first</i> one to effectively achieve both anti-swing and trajectory tracking control in the presence of parametric uncertainties. Not only can the state variables converge to the proposed sliding surface within finite time but also payload swing angles can be completely eliminated; consequently, the working efficiency and operation safety are further guaranteed. The corresponding stability and convergence for the equilibrium point of the closed-loop system are proven by rigorous mathematical analysis based on the Lyapunov techniques and Barbalat’s lemma. Hardware experimental results demonstrate the effectiveness and robustness of the presented controller.

A time optimal trajectory planning method for offshore cranes with ship roll motions

With the fast development of the economy, marine activities are increasing. Due to the advantages of offshore cranes, they are widely used in marine production as effective transportation tools. As a matter of fact, the offshore crane works on the ship known as a typical noninnertial system, which is affected by the ship movement. To tackle this problem, we propose a time optimal trajectory planning method for the considered offshore crane. Specifically, to tackle the couplings between state variables, we show that the offshore crane system is differentially flat with the payload coordinates as the flat outputs. Based on this fact, the planning problems for the jib motion and the rope length are further converted into the planning problems for flat outputs. Then, in order to ensure the trackability of the planned trajectory and improve the safety, we consider a series of physical constraints including the jib luffing motion velocity and acceleration constraints, the rope length varying velocity and acceleration constraints, and the payload swing angle and angular velocity constraints, and then a time optimization problem is further formulated. By utilizing a bisection-based method, the optimal payload transportation time is obtained as well as the corresponding time optimal trajectories. As far as we know, it is the first time optimal trajectory planning method designed for offshore cranes to achieve the fast and accurate payload transportation as well as the payload swing elimination in earth-fixed frame. At last, the effectiveness of the proposed method is verified by simulation tests.

Energy-based nonlinear adaptive control for collaborative transportation systems

As an ideal method for heavy or large payload delivery, collaborative aerial transportation with multiple unmanned aerial vehicles (UAVs) increases the load capacity. However, during the transportation process, collaborative transportation systems are always subject to environmental disturbances and system uncertainties, which poses a great challenge to safe and efficient payload transportation. Existing works without payload angle information in control inputs cannot exhibit satisfactory antiswing performance. To handle the aforementioned issues, this paper proposes a novel control strategy for rapid UAV positioning and payload swing elimination. Specifically, the dynamic model of the collaborative transportation system is described based on a redundant dynamic expression. Then, an artificially constructed UAV-payload unified signal is introduced to enhance the state coupling between the UAV positions and payload swing angles. Based on the newly defined signal, the energy storage function is constructed and the adaptive control law is derived. Additionally, the detailed Lyapunov analysis is provided to prove the system stability and convergence. It is worth noting that the difficulty of the stability analysis is greatly reduced with the help of the established redundant dynamic description. To validate the performance of the proposed control strategy, experimental studies have been carried out in different scenarios. Hardware experimental results show that the proposed method can effectively suppress load swing while ensuring rapid UAV positioning, even with external disturbances.

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.

A New Payload Swing Angle Sensing Device and Its Accuracy.

Measuring the swing angle of a crane load is a relatively well-known but unsatisfactorily solved problem in technical practice. This measurement is necessary for the automatic stabilization of load swing without human intervention. This article describes a technically simple and new approach to solving this problem. The focus of this work is to determine the accuracy of the measuring device. The focus of this work remains on the design, the principle of operation of the equipment, and the determination of accuracy. The basic idea is to apply the strain gauge on an elastic, easily deformable component that is part of the device. One part of the elastic component is fixedly connected to the frame; the other part is connected to the crane rope by means of pulleys close to the rope. In this way, the bending of the elastic component in proportion to the swing angle of the payload is ensured.

Adaptive Control for a Quadrotor Transporting a Cable-Suspended Payload With Unknown Mass in the Presence of Rotor Downwash

This paper investigates the control problem for a quadrotor with a cable-suspended payload (QCSP). A new adaptive control strategy is designed to control the velocity of a volumetric payload with unknown mass in the presence of rotor downwash. The asymptotic stability of the resulting closed-loop system is analysed via the Lyapunov method. Furthermore, a novel structure is designed to suspend the payload on the quadrotor by a cable, and a gyroscope is installed on this structure to measure the payload's swing angle. The designed controller's performance is demonstrated by simulations implemented in a Simulink/SimMechanics environment. The effectiveness of the proposed control scheme is validated in real experiments.

Robust observer-based anti-swing control of 2D-crane systems with load hoisting-lowering

A new model-free robust control scheme for payload swing angle attenuation of two-dimensional crane systems with varying rope length is introduced in this work. The proposed controller consists of a proportional derivative controller, a disturbance observer, and a compensation term that includes a coupling function. A proper design of the coupling function allows attenuating the magnitude of the swing angle, while the disturbance observer permits reducing the effect of internal and external disturbances. Then, a rigorous stability analysis demonstrates that the proposed controller allows the system to follow a desired translational motion and hoisting/lowering the load with small payload oscillations despite the adverse effects caused by internal and external disturbances. In the proposed scheme, a stage devoted to the design of the reference signal is also encompassed. The new methodology is compared to a robust controller and an adaptive scheme. Exhaustive numerical simulations demonstrate that the new controller’s performance outperforms the other control techniques, despite the presence of endogenous and exogenous 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.

An improved method for swing measurement based on monocular vision to the payload of overhead crane

In order to solve the problem that the blurred image of a moving object decreases accuracy in the process of detecting the payload swing angle of an overhead crane based on vision, and the tracking failure caused by the drastic change of grey targets, a robust real-time detection method of the load swing angle of a bridge crane is proposed. This method uses a spherical marker attached to the load, which is insensitive to rotation and tilt when it is detected. First, it uses the mean shift algorithm combined with Kalman filter to track the moving objects in the image plane continuously, and then integrates the method of minimum area circle to detect the spherical marker image in the region of interest accurately and quickly. Finally, combined with the geometric method, the real-time swing angle is calculated. In addition, the angle diagram method is used to increase the speed of calculating the swing angle. The experimental results show that the method is effective for detecting the load target swing angle of different trolley motion speed.

Adaptive integral sliding mode control with payload sway reduction for 4-DOF tower crane systems

An adaptive integral sliding mode control (AISMC) method with payload sway reduction is presented for 4-DOF tower cranes in this paper. The designed controller consists of three parts: The integral sliding mode control is used to provide the robust behavior; the adaptive control is utilized to present the adaptive performance; the swing-damping term is added to suppress and eliminate the payload swing angles. Different from existing sliding mode control methods presenting with chattering phenomenon, the proposed AISMC method is essentially continuous and chattering free. Moreover, the accurate values of the system parameters including the payload mass, the trolley mass, the cable length, the moment of inertia of the jib, the friction-related coefficients are not required for the designed controller due to the adaptive control. Lyapunov-based analysis and LaSalle’s invariance principle are employed to support the theoretical derivations without linearizing the nonlinear dynamics. Experimental results are illustrated to show the superior control performance of the designed controller.

A family of anti-swing motion controllers for 2D-cranes with load hoisting/lowering

Abstract This paper presents a methodology for designing controllers that attenuate the payload swing angle in two-dimensional overhead crane systems with varying rope length. The proposed scheme is based on the proper construction of a design function, which combines the coordinate of the translational motion of the crane with that corresponding to the swing angle. The proposed methodology shows how to design a family of functions that can be used not only to attenuate the swing angle but also to follow a desired motion. Then, the controller is implemented in combination with a trajectory design stage based on S-curves. The proposed scheme is compared with a controller with a proportional derivative structure and an adaptive controller. Numerical and experimental results validate the proposed methodology and show the effectiveness of the proposed controller even when the system is being affected by state estimation errors and external disturbances.

Energy-Based Nonlinear Adaptive Control Design for the Quadrotor UAV System With a Suspended Payload

In this paper, the control problem for an underactuated quadrotor unmanned aerial vehicle (UAV) with a suspended payload is investigated. An energy-based nonlinear controller is proposed that is able to control the quadrotor UAV's position and the payload's swing angle asymptotically. An adaptive control design is developed to compensate for the unknown length of the cable which is used to connect the UAV and the payload. The Lyapunov-based stability analysis is employed together to prove the stability of the closed-loop system. Detailed real-time experimental results illustrate the good performance of the proposed controller.