Active Heave Compensation System Research Articles

Cascade NMPC-PID control strategy of active heave compensation system for ship-mounted offshore crane

In this paper, the problem associated with active heave motion compensation during heavy-lift operations performed by ship-mounted offshore cranes beneath rough marine environment is investigated. To effectively decouple the correlated motion of the suspended payload from the support vessel via the secondary regulated active heave compensation (SRAHC) system, a novel hierarchical control strategy is proposed by integrating a cascade control structure with an adaptive robust control scheme that incorporates a vertical motion forecast algorithm based on autoregressive integrated moving average (ARIMA) model, a conventional proportional-integral-derivative (PID) framework, and a nonlinear model predictive control (NMPC) method. The introduction of the cascade structure is motivated by its prompt error response against control lag and efficient system order reduction for computational burden alleviation, which forms a crucial foundation for the NMPC-based real-time regulation of PID gains, ensuring optimal evolution of the SRAHC system while improving its practical feasibility. Furthermore, the enhancements in heave compensation and trajectory tracking performance, noise resistance, constraint satisfaction, and engineering application potential of the proposal are demonstrated through a thorough comparative analysis conducted in a practical co-simulation research system.

Research on Three-Closed-Loop ADRC Position Compensation Strategy Based on Winch-Type Heave Compensation System with a Secondary Component

To mitigate the interference of waves on an offshore operation ship, heave compensation systems find widespread application. The performance of heave compensation systems significantly influences the efficiency and safety of maritime operations. This study established a mathematical model for a winch-based active heave compensation system. It introduced a three-loop active disturbance rejection control (ADRC) strategy that encompasses piston position control, winch speed control, and load-displacement control to enable the real-time estimation and compensation of system disturbances, thereby enhancing the performance of the heave compensation system. To assess the effectiveness of this control strategy, this study employed Matlab/Simulink and AMESim to construct a co-simulation model and conducted a comparative analysis with traditional proportional integral derivative (PID) control systems. The research findings indicate that the three-loop ADRC position control strategy consistently delivered superior compensation performance across various operational scenarios.

NMPC-PID control of secondary regulated active heave compensation system for offshore crane

In this paper, an offshore crane driven by a secondary controlled unit (SCU) which offers advantages in terms of high dynamic behavior and energy efficiency is investigated. To counteract the negative impact of the support vessel's heave motion on the station-keeping and trajectory tracking performance of heavy payload, an adaptive robust control scheme for the secondary regulated active heave compensation (AHC) system is proposed based on the combination of a nonlinear model predictive control (NMPC) strategy, a conventional proportional-integral-derivative (PID) control scheme and a vessel heave motion prediction algorithm. The motivation of utilizing the PID-based control structure is given by the excellent resistance against irregular external disturbances and robust capability to eliminate the uncertainties, with real-time tuning gains provided by the NMPC synthesized with the autoregressive integrated moving average (ARIMA) model to ensure optimal evolution that satisfies state and input constraints while accounting for model nonlinearities. Comparative simulation studies in the practical Simulink-based mechanical-electrical-hydraulic research system demonstrate the superior tracking and heave compensation performance, strong robustness, constraint satisfaction, and energy efficiency of the proposal.

Cascade Control of Active Heave Compensation Nonlinear System for Marine Crane

During the rough marine environment, heave compensation is used to offset the heave motion of the vessel when a marine crane lifts and lands the load. Thus, load motion and vessel motion are realized decoupled. In previous studies, the interference items such as hydraulic cylinder friction, underwater drag force and nonlinear friction in the active heave compensation system of a marine hydraulic crane are compensated as a concentrated interference force to be estimated. In this paper, we disassembled the interference items; the disturbance observer and adaptive rate are designed to estimate unmodeled disturbance force and system uncertain parameters, respectively; and we designed an active heave compensator with the adaptive nonlinear cascade controller which has the disturbance observer (DOB-ANCC). For the heave compensation of load displacement, this paper derived the control law of the nonlinear system model based on the backstepping method. The outer loop control is displacement control and the inner loop control is pressure control. The simulation verifies the effectiveness of the control strategy proposed in this paper and the availability of heave displacement compensation for a marine crane hoisting load. The compensation efficiency of the designed controller (DOB-ANCC) for the heave motion of the load can reach more than 95%, and the maximum displacement tracking error of the controller can reach ± 0.035 m.

Predictive Control of a Heaving Compensation System Based on Machine Learning Prediction Algorithm

Floating structures have become a major part of offshore structure communities as offshore engineering moves from shallow waters to deeper ones. Floating installation ships or platforms are widely used in these engineering operations. Unexpected wave-induced motions affect floating structures, especially in harsh sea conditions. Horizontal motions on the sea surface can be offset by a dynamic positioning system, and heave motions can be controlled by a heave compensation system. Active heave compensation (AHC) systems are applied to control vertical heave motions and improve safety and efficiency. Predictive control based on machine learning prediction algorithms further improves the performance of active heave compensation control systems. This study proposes a predictive control strategy for an active heave compensation system with a machine learning prediction algorithm to minimise the heave motion of crane payload. A predictive active compensation model is presented to verify the proposed predictive control strategy, and proportion–integration–differentiation control with predictive control is adopted. The reliability of back propagation neural network (BPNN) and long short-term memory recurrent neural network (LSTM RNN) prediction algorithms is proven. The influence of the predictive error on compensation performance is analysed by comparing predictive feedforward cases with actual-data feedforward cases. Predictive feedforward control with regular and irregular wave conditions is discussed, and the possible strategies are examined. After implementing the proposed predictive control strategy based on a machine learning algorithm in an active heave compensation system, the heave motion of the payload is reduced considerably. This investigation is expected to contribute to the motion control strategy of floating structures.

Modeling and Adaptive Boundary Robust Control of Active Heave Compensation Systems

Heave compensation systems are essential for operations’ safety, reliability, and efficiency in harsh offshore environments. This paper investigates the vibration suppression problem of a type of deep-sea robot with the length of time variation and harsh operating environments for active heave compensation systems, where hydraulic heave compensators implement actuators with input nonlinearity, model coupling, and unknown nonlinear disturbances. A robust adaptive output feedback control scheme based on the backstepping control method is designed to eliminate deep-ocean robot vibration, where the adaptive law handles the system parameter uncertainty. Meanwhile, a nonlinear disturbance observer (NDO) is introduced to overcome the effects of random disturbances and model coupling. In addition, the stability of the whole system is proved according to Lyapunov’s theory, and the scheme is shown to be feasible by theoretical analysis. Finally, a comparative simulation study was conducted to validate the effectiveness of the proposed controller.

Dynamic Analysis of Active Heave Compensation System for Marine Winch under the Impact of Irregular Waves

The six-degree-of-freedom (6 DOF) motion of the mother ship, especially the heave motion, brings difficulties to offshore operations and even causes safety accidents. To ensure the reliability of the launch and recovery system when the active heave compensation (AHC) function works, its dynamic characteristics are analyzed. Firstly, the dynamic model of the launch and recovery system with a rigid rope is constructed, and the mathematical simulation of the launch and recovery system without the AHC function under the excitation of irregular waves is completed. Secondly, a flexible rope based on the finite element method is established, and the dynamic responses of the launch and recovery system with AHC function under different conditions are compared with those without AHC function. The simulation results demonstrate that the dynamic responses of the system are related to the load, the underwater penetration, and the sea condition. In detail, the increase of the load leads to an increase in the dynamic response of the system. In essence, the underwater penetration affects the dynamic response of the system by affecting the activity of load acceleration. Therefore, a short rope is preferred in the maritime operations. Moreover, the harsh sea condition usually causes an undesirable effect of AHC function. In summary, the overall work is conductive to the modeling of the launch and recovery system, as well as the development of AHC technology so as to improve the quality of offshore operations in the future.

Modeling and simulation analysis of active heave compensation control system for electric-driven marine winch under excitation of irregular waves

The six-degree-of-freedom (6 DOF) motion of the mother-ship, which is caused by wave fluctuation, makes offshore operations difficult. To solve this problem, various heave compensation systems were proposed, as well as the law of wave motion. These heave compensation systems included passive heave compensation system, semi-active heave compensation system, and active heave compensation (AHC) system. However, the empirical formula of wave motion is not suitable for practical offshore operations, and rare AHC systems take the characteristic of compensation into consideration. To study the compensation characteristic of the AHC system based on electric-driven marine winch in the actual sea condition and improve the accuracy of compensation, this work uses the measured data of wave motion, and deduces the motion equations of multi-axial driving system. By substituting the above elements into the AHC system and designing the sliding mode controller (SMC), the simulation results show the ideal compensation effect of the system. By comparing with experimental results, it is concluded that the driving system operates in according with the specified states, and the compensation performance of system is effective. The overall work is conductive to the research on AHC system, as well as the exploitation of marine resources.

Adaptive Control Based on Neural Network and Beetle Antennae Search Algorithm for an Active Heave Compensation System

Adaptive Control Based on Neural Network and Beetle Antennae Search Algorithm for an Active Heave Compensation System

Modeling of Active Heave Compensation System for Seafloor Drill

Aiming at the influences of wave in the process of launch & recovery of the seafloor drill, a velocity sensor is used to gather the data of the heave motion of ship, and a mathematical model of active heave compensation hydraulic serve control system for seafloor drill is established. The simulation of this model based on PID control is performed. The results show that the heave motion compensation control of seafloor drill using PID control makes the tracking accuracy more than 90%. This will improves the reliability and security of the seafloor drill in the process of launch and recovery.

Hierarchical NMPC–ISMC of active heave motion compensation system for TMS–ROV recovery

This study reveals the operating risk of cable breaking when the TMS–ROV recovery is carried out beneath rough ocean waves. To release the negative impact of the support vessels vertical heave motion on the station-keeping and position tracking performance of TMS, a robust hierarchical control scheme for a hydraulic-driven winch-based active heave compensation (AHC) system is proposed based on the combination of a nonlinear model predictive control (NMPC) strategy, an integral sliding mode control (ISMC) scheme and a vessel heave motion prediction algorithm. The motivation of utilizing the ISMC-based internal level combined with the integral state transformation technique is given by the robust capability to eliminate the uncertainties, which provides the nominal model for NMPC-based external level to guarantee the optimal evolution satisfying the state and input constraints and resisting the dynamical hysteresis caused by the employed extremely long cable length for deep-sea operation. Comparative simulation studies contribute to the analysis of the surge in cable tension during the TMS–ROV recovery and demonstrate the superior tracking and heave compensation performance, strong robustness and constraint satisfaction of the proposal.

Methodologies for landing autonomous aerial vehicles on maritime vessels

One of the key challenges to the safe operation of UAVs at sea is the relative motion that exists between the UAV and ship during landing. The scope of this work is the development and evaluation of methodologies for improving UAV landing performance. The new methodologies are known as the Signal Prediction Algorithm (SPA), Active Heave Compensation (AHC) and the Landing Period Indicator (LPI). To promote interoperability, the methodologies do not require any specific ship equipment.To evaluate the methodologies on an existing comprehensive UAV model, ShipMo3D was used to generate 105 sets of ship motion in sea states 2–6, headings 0–180∘ and speeds 6–10 knots. Within the simulation the UAV, equipped with a Light Detection and Ranging (LIDAR) system, measures the ship motion in situ. Using the Signal Prediction Algorithm (SPA), the UAV forecasts the ship motion and potential landing opportunities. The UAV can also use the SPA and the AHC system to maintain a safe hover position above the ship deck and determine landing trajectories with a specific touchdown velocity. The UAV can also employ the novel Landing Period Indicator (LPI) system which calculates an estimate of the ship's energy and determines opportune times for safe landings.The results indicate that the methodologies can improve the landing performance of autonomous helicopters. For the 105 sets of ship motion, using the combination of the SPA, AHC, and LPI improved landing success by up to 34% when compared to a common landing controller.

Study on Energy Recovery Performance of Linear Active Heave Compensation System

In order to verify the feasibility of the energy recovery of the linear active heave compensation device under the descent compensation condition, the author established a schematic diagram of the hydraulic system based on the heave compensation principle, performed a simulation analysis of the hydraulic system model in a cycle, analysed energy loss of the system under specific sea conditions. Therefore, it is concluded that the gravity potential energy of the load under the descent compensation condition has great potential for recovery. Based on the results of the demonstration, the article proposes an electro-hydraulic energy recovery system of the linear active heave compensation device based on a hydraulic motor-generator. The system model is simulated and analysed in a single cycle under standard operating conditions. The results show that: When the system parameters match reasonably, the heave compensation device has a higher compensation accuracy. The energy recovery rate of the system under the down compensation condition reaches 21.6%, and the effect of energy saving is great. At the same time, simulation analysis shows that under the premise of ensuring the compensation accuracy, changes in the quantitative motor displacement and the viscous friction coefficient of the generator will affect the energy recovery efficiency to varying degrees.

ADRC-ESMPC active heave compensation control strategy for offshore cranes

ABSTRACT Heave compensation system is a vital part for offshore cranes. Most of the existing active heave controllers focus on compensating the wave-induced heave motion while the correction for the nonlinear properties of the hydraulic motor system such as deadzone and input saturation is still an open problem. This paper presents an ADRC-ESMPC double-loop controller for a hydraulic valve-based active heave compensation system. Active disturbance rejection control (ADRC), which has advantages such as model independence, strong robustness and simple structure, is used in the outer loop to compensate for the external perturbations, frictions and parametric uncertainties and generate the desired angular displacement for the inner loop. In consideration that the hydraulic valve is characterised by the presence of deadzone and input saturation, the equivalent saturation model predictive control (ESMPC) approach is used in the inner loop to ensure that the hydraulic motor tracks the desired angular displacement. The effectiveness of the proposed controller is evaluated with simulations.

Design and Research of Active Heave Compensation System Based on Laser Ranging Sensor

Marine resource exploitation and marine cargo transportation were increasingly frequent. Due to the impact of the marine environment, ships or platforms were affected. In this paper, a servo electric cylinder was used as a wave compensation actuator to design a wave compensation system. The laser sensor was used to measure the displacement in the direction of the heave platform, and the obtained displacement was applied to the wave compensation in the heave direction to verify the feasibility of the compensation system.

Reference-Point Algorithms for Active Motion Compensation of Towed Bodies

Active heave compensation systems are typically single-degree-of-freedom systems that operate vertically to attenuate the vertical effects of wave motion. To apply compensation to towed bodies, which experience significant multiple-degree-of-freedom disturbances, a generalized motion compensation system using a “reference-point algorithm” is required that determines the length of a tow cable that should be reeled in or reeled out by an on-board winch system in response to external wave motion. This paper proposes, implements, and assesses four different reference-point algorithm approaches in both simulation and experimental environments. Of the proposed reference-point algorithms, the method that directly accounts for the tow cable angle proved to be most effective in both simulation and experimentation. It was found that there was little improvement between real-time measurements of the tow cable angle and a constant nominal tow cable angle—indicating a potential cost saving opportunity through the avoidance of real-time sheave-angle measurement.

A study on load position control and vibration attenuation in crane operation using sub-actuator

The main purpose of any crane system is to move a load to a specified place. Accurate load positioning in the presence of unpredictable external factors is an important issue when operating a crane. Attenuation of load vibration during crane operation is immensely critical in order to satisfy rigorous requirements for safety and efficiency. When a crane is installed and operated on a vessel at sea, work conditions become even more difficult and thus require more stringent attention to load positioning and attenuation of load vibration. At sea, this process is complicated due to factors such as waves and wind, making accurate crane operation nearly impossible. For these reasons, active heave compensation systems have been developed to suppress the effects of disturbances raised from the harsh sea environment including vessel motions. This paper explores the suppression method of unexpected vertical vibration of load. Unlike past research on the topic, this research includes rope dynamics in the control system design for suppressing load vibration. In addition, this research considers uncertain disturbances—vessel motions not controlled by any active force that result in undesirable heave motion of a crane. Load motion is indirectly estimated using a load cell because we do not yet have any useful tool to measure it directly. In the considered crane system, two winches were used, one for moving the load and the other for suppressing residual vibration. To evaluate the proposed control strategy and system performance, several control techniques were applied: proportional–integral–derivative control, sliding mode control, and feedback linearization control methods.

State Constrained Variable Structure Control for Active Heave Compensators

Heave compensation systems are widely used to decouple the load motion from wave-induced vessel motion for the equipment handling on the ocean. Researches have been made to achieve successful compensation, yet few of them discusses the inherent constraints of the systems, such as bounded compensator’s stroke and max actuator’s velocity. This paper presents a solution for active heave compensation systems with such constraints by means of variable structure control. The controller’s complexity on design procedures and effectiveness are compared with a trajectory planning control method which turns out that the variable structure controller is more suitable to apply to the active heave compensators. The back-stepping method is used to robustly stabilize this variable structure system and for the aim of a decrease on the high robust gain due to uncertain friction term, a modified decoupled friction observer is used which is also verified by both theoretical and experimental analyses. To compensate for the time delay of the motion reference unit (MRU), a heave prediction algorithm is used. The experimental results show that most heave motion can be compensated when the motion and its velocity are feasible, while no hit occurs otherwise.

Design of The Test Stand for Hydraulic Active Heave Compensation System

Abstract The article presented here described the design of a test stand for hydraulic active heave compensation system. The simulation of sea waves is realized by the use of hydraulic cylinder. A hydraulic motor is used for sea waves compensation. The hydraulic cylinder and the hydraulic motor are controlled by electrohydraulic servo valves. For the measurements Authors used displacement sensor and incremental encoder. Control algorithm is implemented on the PLC. The performed tests included hydraulic actuator and hydraulic motor step responses.

Modelling and simulation of a hydraulic active heave compensation system

The following work presents modelling, simulation and results of hydraulic motor and hydraulic cylinder position measurement for a hydraulic active heave compensation system (AHC). In order to perform experimental research the authors developed a test stand. A hydraulic cylinder is used to carry out a simulation of sea waves. The development of a test stand made it possible to compare the simulation with the experimental results. A hydraulic motor is used for compensation of sea waves. Optimization of design parameters for such systems can be done by analysing a model simulation. The main components of this system were modelled. This model was implemented in simulation software Mathlab Simulink and its dynamic performance was tested. The Authors presented the simulation and the experimental results for main components of a hydraulic active heave compensation system.