Pub Date : 2024-11-15DOI: 10.1016/j.oceaneng.2024.119682
Qiang Ding, Fang Deng, Zhiyu Du, Shuai Zhang
This study investigates the trajectory tracking problem of dynamic positioning ships under input constraints, model uncertainties and time-varying environmental disturbances. Firstly, the unmodeled nonlinear dynamics of the dynamic positioning (DP) ship and the external disturbances are integrated together as lumped uncertainties, and a fixed-time uncertainty and disturbance estimator (FTUDE) based on an integral sliding mode is developed to compensate effects of the lumped uncertainties. Then, the event-triggered nonlinear model predictive control (ENMPC) trajectory tracking control strategy for DP ship is established by introducing the event-triggered mechanism into nonlinear model predictive control, which can reduce the computational resource consumption while ensuring control effectiveness. The feasibility and input-to-state stability of ENMPC with FTUDE have been proved. Comparison simulations have been conducted to validate the effectiveness and superiority of the proposed method.
{"title":"FTUDE based event-triggered NMPC for trajectory tracking of dynamic positioning ships under input constraints","authors":"Qiang Ding, Fang Deng, Zhiyu Du, Shuai Zhang","doi":"10.1016/j.oceaneng.2024.119682","DOIUrl":"10.1016/j.oceaneng.2024.119682","url":null,"abstract":"<div><div>This study investigates the trajectory tracking problem of dynamic positioning ships under input constraints, model uncertainties and time-varying environmental disturbances. Firstly, the unmodeled nonlinear dynamics of the dynamic positioning (DP) ship and the external disturbances are integrated together as lumped uncertainties, and a fixed-time uncertainty and disturbance estimator (FTUDE) based on an integral sliding mode is developed to compensate effects of the lumped uncertainties. Then, the event-triggered nonlinear model predictive control (ENMPC) trajectory tracking control strategy for DP ship is established by introducing the event-triggered mechanism into nonlinear model predictive control, which can reduce the computational resource consumption while ensuring control effectiveness. The feasibility and input-to-state stability of ENMPC with FTUDE have been proved. Comparison simulations have been conducted to validate the effectiveness and superiority of the proposed method.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119682"},"PeriodicalIF":4.6,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.oceaneng.2024.119640
Thiago S. Hallak, José F. Gaspar, C. Guedes Soares
The new methodology based on generalised coordinates for the analysis of floating multi-body systems with nonlinear geometric constraints is developed, and it is demonstrated through numerical application for a hybrid floating wind-wave platform consisting of a floating offshore wind turbine and an articulated wave energy converter that moves a hydraulic piston. The formulation is applied to achieve explicit formulae regarding the dynamic response in a low-dimensional scenario used to verify a post-processing code. The verification considers the nonlinear geometric constraints, hydrodynamic interaction, the dynamics of articulated arms, and the dynamics of hydraulic power take-off systems. An analytical expression for the system's natural frequencies is attained and verified likewise. The results presented in this paper indicate significant improvement in the simulation and analysis of multi-degrees-of-freedom nonlinear hydrodynamic systems, which will ultimately be necessary for designing efficient hybrid floating wind-wave platforms.
{"title":"A mathematical model for the dynamic analysis of multi-body floating platforms with complex mechanical constraints","authors":"Thiago S. Hallak, José F. Gaspar, C. Guedes Soares","doi":"10.1016/j.oceaneng.2024.119640","DOIUrl":"10.1016/j.oceaneng.2024.119640","url":null,"abstract":"<div><div>The new methodology based on generalised coordinates for the analysis of floating multi-body systems with nonlinear geometric constraints is developed, and it is demonstrated through numerical application for a hybrid floating wind-wave platform consisting of a floating offshore wind turbine and an articulated wave energy converter that moves a hydraulic piston. The formulation is applied to achieve explicit formulae regarding the dynamic response in a low-dimensional scenario used to verify a post-processing code. The verification considers the nonlinear geometric constraints, hydrodynamic interaction, the dynamics of articulated arms, and the dynamics of hydraulic power take-off systems. An analytical expression for the system's natural frequencies is attained and verified likewise. The results presented in this paper indicate significant improvement in the simulation and analysis of multi-degrees-of-freedom nonlinear hydrodynamic systems, which will ultimately be necessary for designing efficient hybrid floating wind-wave platforms.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119640"},"PeriodicalIF":4.6,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.oceaneng.2024.119729
Jinyong Guo , Bo Han , Zhenlin Ma , Bo-nan Zhang , Meng Guo , Ben He
During the service period, the offshore wind turbine (OWT) must withstand multiple fluid loads of wind, waves and ocean currents. While the dynamic characteristics of OWT are affected by the coupling effect between the wind turbine structure, foundation, and fluid environment. Therefore, a complete model with geometrical scaling of 1:100 of the NERL-5MW wind turbine was manufactured and a series of model tests were conducted in the integrated Wind Tunnel-Flume-Foundation experimental system. The strain response characteristics of the monopile foundation were studied for the first time while the OWT under real fluid conditions. The strain response characteristics of OWT monopile foundation in the real fluid were studied for the first time. The experimental results revealed that the loading state, load intensity, and OWT operating state have significant effects on the dynamic strain response of the monopile. Under the coupling effect of complex fluid loads, the effect of waves enhances the strain response in the top region of the monopile foundation, which is attributed to the fact that the deformation of the foundation has amplified the effect of wind load acting on the upper part of OWT. Moreover, the dominant role of aerodynamic loads on the dynamic response of the OWT becomes more pronounced as the load intensity increases. Therefore, coupling effect between the influence of aerodynamic loads acting on the top and the impact of the hydrodynamic load acting on the foundation cannot be ignored.
{"title":"Research on the strain response of offshore wind turbine monopile foundation through integrated fluid-structure-seabed model test","authors":"Jinyong Guo , Bo Han , Zhenlin Ma , Bo-nan Zhang , Meng Guo , Ben He","doi":"10.1016/j.oceaneng.2024.119729","DOIUrl":"10.1016/j.oceaneng.2024.119729","url":null,"abstract":"<div><div>During the service period, the offshore wind turbine (OWT) must withstand multiple fluid loads of wind, waves and ocean currents. While the dynamic characteristics of OWT are affected by the coupling effect between the wind turbine structure, foundation, and fluid environment. Therefore, a complete model with geometrical scaling of 1:100 of the NERL-5MW wind turbine was manufactured and a series of model tests were conducted in the integrated Wind Tunnel-Flume-Foundation experimental system. The strain response characteristics of the monopile foundation were studied for the first time while the OWT under real fluid conditions. The strain response characteristics of OWT monopile foundation in the real fluid were studied for the first time. The experimental results revealed that the loading state, load intensity, and OWT operating state have significant effects on the dynamic strain response of the monopile. Under the coupling effect of complex fluid loads, the effect of waves enhances the strain response in the top region of the monopile foundation, which is attributed to the fact that the deformation of the foundation has amplified the effect of wind load acting on the upper part of OWT. Moreover, the dominant role of aerodynamic loads on the dynamic response of the OWT becomes more pronounced as the load intensity increases. Therefore, coupling effect between the influence of aerodynamic loads acting on the top and the impact of the hydrodynamic load acting on the foundation cannot be ignored.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119729"},"PeriodicalIF":4.6,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.oceaneng.2024.119613
Hongsheng Zhang , Zhongquan Huang , Xin Jin , Yong Yue , Yiming Chen , Mengjie Luo
Considering the irrationality and limitations of current reviews about dampers for offshore wind turbine (OWT), this paper re-investigates a comprehensive review of the research status and latest developments of OWT based on their structural composition and working principles. Beginning with an emphasis on mainstream tuned mass dampers (TMD) and tuned liquid dampers (TLD), the section on TMD analyzes the sliding structure, pendulum structure, and widely used multi-TMD deployments. The section on TLD analyzes the single-surface liquid sloshing structure and multi-surface liquid column structure. Introducing a variety of novel OWT dampers that have emerged in recent years, including magnetorheological elastomer (MRE), KDamper, shape memory alloys (SMAS), nonlinear energy sink (NES), high damping viscoelastic damper (HVED), amplified damping transfer system (ADTS), and floating absorber damper (FAD). Concluding by summarizing the characteristics, principles, advantages and disadvantages of the dampers discussed. It also suggests promising directions for future development of OWT dampers, such as mixed structures, mixed deployment, additional damping, etc. This paper serves as a valuable reference for researchers to grasp the most recent advancements, enhancing their understanding of damping systems and providing insightful guidance for engineers to select the most suitable dampers for applications.
{"title":"A review of dampers for offshore wind turbines","authors":"Hongsheng Zhang , Zhongquan Huang , Xin Jin , Yong Yue , Yiming Chen , Mengjie Luo","doi":"10.1016/j.oceaneng.2024.119613","DOIUrl":"10.1016/j.oceaneng.2024.119613","url":null,"abstract":"<div><div>Considering the irrationality and limitations of current reviews about dampers for offshore wind turbine (OWT), this paper re-investigates a comprehensive review of the research status and latest developments of OWT based on their structural composition and working principles. Beginning with an emphasis on mainstream tuned mass dampers (TMD) and tuned liquid dampers (TLD), the section on TMD analyzes the sliding structure, pendulum structure, and widely used multi-TMD deployments. The section on TLD analyzes the single-surface liquid sloshing structure and multi-surface liquid column structure. Introducing a variety of novel OWT dampers that have emerged in recent years, including magnetorheological elastomer (MRE), KDamper, shape memory alloys (SMAS), nonlinear energy sink (NES), high damping viscoelastic damper (HVED), amplified damping transfer system (ADTS), and floating absorber damper (FAD). Concluding by summarizing the characteristics, principles, advantages and disadvantages of the dampers discussed. It also suggests promising directions for future development of OWT dampers, such as mixed structures, mixed deployment, additional damping, etc. This paper serves as a valuable reference for researchers to grasp the most recent advancements, enhancing their understanding of damping systems and providing insightful guidance for engineers to select the most suitable dampers for applications.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119613"},"PeriodicalIF":4.6,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.oceaneng.2024.119725
Lei Zhang , YuJing Deng , Jinhua Hu , Danping Ren , Jijun Zhao
Underwater target tracking accuracy is often hindered by acoustic wave propagation paths and communication delays, while long-distance communication nodes shorten the system’s lifetime due to high energy consumption. To address this challenge, we present an underwater multi-hop target tracking algorithm based on a bidirectional modified sound speed profile model (MHOP-BMSSP). MHOP-BMSSP obtains the transmission time using the sound speed profile model and correct transmission time with bidirectionally multiplexing nodes flight time. On the other hand, MHOP-BMSSP utilizes hydroacoustic system connectivity to divide the communication radius based on node density, which reduces transmission energy consumption through multi-hop communication. Nodes are dynamically selected based on hop information and residual energy with different communication radii, while other nodes enter sleep. The selected nodes are used in a ranging model to obtain measurement values. Finally, the difference between observation and measurement values is used to adaptively adjust the measurement noise value of the Unscented Kalman Filter algorithm to complete the adaptive tracking of the nodes. Experimental results show that MHOP-BMSSP improves network tracking accuracy and efficiency and effectively extends network lifetime.
{"title":"Underwater multi-hop target tracking algorithm based on bidirectional modified sound speed profile model","authors":"Lei Zhang , YuJing Deng , Jinhua Hu , Danping Ren , Jijun Zhao","doi":"10.1016/j.oceaneng.2024.119725","DOIUrl":"10.1016/j.oceaneng.2024.119725","url":null,"abstract":"<div><div>Underwater target tracking accuracy is often hindered by acoustic wave propagation paths and communication delays, while long-distance communication nodes shorten the system’s lifetime due to high energy consumption. To address this challenge, we present an underwater multi-hop target tracking algorithm based on a bidirectional modified sound speed profile model (MHOP-BMSSP). MHOP-BMSSP obtains the transmission time using the sound speed profile model and correct transmission time with bidirectionally multiplexing nodes flight time. On the other hand, MHOP-BMSSP utilizes hydroacoustic system connectivity to divide the communication radius based on node density, which reduces transmission energy consumption through multi-hop communication. Nodes are dynamically selected based on hop information and residual energy with different communication radii, while other nodes enter sleep. The selected nodes are used in a ranging model to obtain measurement values. Finally, the difference between observation and measurement values is used to adaptively adjust the measurement noise value of the Unscented Kalman Filter algorithm to complete the adaptive tracking of the nodes. Experimental results show that MHOP-BMSSP improves network tracking accuracy and efficiency and effectively extends network lifetime.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119725"},"PeriodicalIF":4.6,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.oceaneng.2024.119674
D.A. Dao, J. Grabe
As renewable energy demand increases, protecting subsea cables from ship anchor damage has become essential. This research comprises numerical simulations of the anchor penetration process in Baltic Sea sand (for an AC-14, a Hall and a Spek anchor). We apply a coupled Eulerian–Lagrangian (CEL) framework and a hypoplasticity constitutive model to analyze the influence of different anchor characteristics on penetration depth and seabed stress distributions. We conducted investigations under high velocities ( m/s) with focus on inertial effects only. Furthermore, this study introduces stress circles to visualize a simplified anchor-induced spatial stress distribution in the seabed. Findings show that heavier anchors and slower drag velocities generally result in deeper anchor penetrations. Fluke geometry significantly affects penetration depth, with pointed designs penetrating more deeply. The observed trends align with previous results from centrifuge tests and numerical modeling of ship anchors. This research improves understanding of soil–structure interaction in maritime environments, offering insights for the protection of subsea installations in the Baltic Sea and similar regions.
{"title":"Numerical assessment of ship anchor penetration depth in Baltic Sea Sand: Implications for subsea cable burial","authors":"D.A. Dao, J. Grabe","doi":"10.1016/j.oceaneng.2024.119674","DOIUrl":"10.1016/j.oceaneng.2024.119674","url":null,"abstract":"<div><div>As renewable energy demand increases, protecting subsea cables from ship anchor damage has become essential. This research comprises numerical simulations of the anchor penetration process in Baltic Sea sand (for an AC-14, a Hall and a Spek anchor). We apply a coupled Eulerian–Lagrangian (CEL) framework and a hypoplasticity constitutive model to analyze the influence of different anchor characteristics on penetration depth and seabed stress distributions. We conducted investigations under high velocities (<span><math><mrow><mi>v</mi><mo>≥</mo><mn>1</mn></mrow></math></span> <!--> <!-->m/s) with focus on inertial effects only. Furthermore, this study introduces stress circles to visualize a simplified anchor-induced spatial stress distribution in the seabed. Findings show that heavier anchors and slower drag velocities generally result in deeper anchor penetrations. Fluke geometry significantly affects penetration depth, with pointed designs penetrating more deeply. The observed trends align with previous results from centrifuge tests and numerical modeling of ship anchors. This research improves understanding of soil–structure interaction in maritime environments, offering insights for the protection of subsea installations in the Baltic Sea and similar regions.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119674"},"PeriodicalIF":4.6,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.oceaneng.2024.119701
N. Nozari, B. Asgarian, M. Zarrin
Quantitative assessment of environmental conditions and their loading effects is crucial for the optimal design of marine structures, especially offshore platforms subject to extreme environmental conditions. Wave load, particularly irregular wave load, significantly influences the structural response and ultimate strength of jacket-type offshore platforms (JTOPs) throughout their operational life. The dynamic nature of these irregular wave loads necessitates the use of advanced time history analysis to accurately capture their impact. This study aims to enhance the understanding of how foundation conditions impact failure modes and the structural response of JTOPs through an innovative incremental irregular wave dynamic analysis procedure. By focusing on an existing steel jacket-type platform in the Persian Gulf, this research evaluates six models with varying soil profiles and pile conditions to assess their effects on structural performance. The application of incremental irregular wave dynamic analysis provides a more precise and realistic modeling of wave impacts compared to traditional methods. The findings demonstrate that stronger soil profiles and improved pile conditions significantly enhance structural integrity, particularly under extreme loading conditions. Specifically, optimizing pile configurations is critical for enabling the structure to endure larger waves, whereas variations in the yield stress of steel material have a lesser impact on the platform's response. Additionally, the dynamic results are compared with pushover analysis, which serves as a benchmark to evaluate the accuracy and effectiveness of the pushover analysis compared to incremental irregular wave analysis method used in this study.
{"title":"Effects of foundation conditions on failure modes of jacket type offshore platforms using incremental irregular wave dynamic analysis","authors":"N. Nozari, B. Asgarian, M. Zarrin","doi":"10.1016/j.oceaneng.2024.119701","DOIUrl":"10.1016/j.oceaneng.2024.119701","url":null,"abstract":"<div><div>Quantitative assessment of environmental conditions and their loading effects is crucial for the optimal design of marine structures, especially offshore platforms subject to extreme environmental conditions. Wave load, particularly irregular wave load, significantly influences the structural response and ultimate strength of jacket-type offshore platforms (JTOPs) throughout their operational life. The dynamic nature of these irregular wave loads necessitates the use of advanced time history analysis to accurately capture their impact. This study aims to enhance the understanding of how foundation conditions impact failure modes and the structural response of JTOPs through an innovative incremental irregular wave dynamic analysis procedure. By focusing on an existing steel jacket-type platform in the Persian Gulf, this research evaluates six models with varying soil profiles and pile conditions to assess their effects on structural performance. The application of incremental irregular wave dynamic analysis provides a more precise and realistic modeling of wave impacts compared to traditional methods. The findings demonstrate that stronger soil profiles and improved pile conditions significantly enhance structural integrity, particularly under extreme loading conditions. Specifically, optimizing pile configurations is critical for enabling the structure to endure larger waves, whereas variations in the yield stress of steel material have a lesser impact on the platform's response. Additionally, the dynamic results are compared with pushover analysis, which serves as a benchmark to evaluate the accuracy and effectiveness of the pushover analysis compared to incremental irregular wave analysis method used in this study.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119701"},"PeriodicalIF":4.6,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.oceaneng.2024.119743
Zaopeng Dong , Wenjie Zhou , Fei Tan , Baolin Wang , Zhaoyang Wen , Yuanchang Liu
An adaptive fuzzy sliding mode control scheme based on data feedback is proposed in this paper, in order to achieve the trajectory tracking control of underactuated unmanned surface vehicles (USVs) in the present of unknown model parameters and environmental disturbances. Considering the problem of unknown model parameters, based on the feedback of sailing data, an online identification algorithm is designed to obtain real-time model parameters of USVs, which are used to establish the real-time simultaneous models of USV formation. A fuzzy control algorithm is introduced into the sliding mode controller design process to reduce convergence time and eliminate the chattering of the controller. Furthermore, a first-order low-pass filter is proposed to overcome the "differential explosion" issue, and a second-order differential tracker is designed to mitigate the jitter effects caused by higher-order derivatives of the lateral velocity. In addition, a nonlinear disturbance observer is developed to estimate and compensate the composite disturbances caused by real-time modeling inaccuracies and ocean environment disturbances. Finally, the effectiveness and robustness of the proposed control scheme are verified by several simulation experiment cases.
{"title":"Simultaneous modeling and adaptive fuzzy sliding mode control scheme for underactuated USV formation based on real-time sailing state data","authors":"Zaopeng Dong , Wenjie Zhou , Fei Tan , Baolin Wang , Zhaoyang Wen , Yuanchang Liu","doi":"10.1016/j.oceaneng.2024.119743","DOIUrl":"10.1016/j.oceaneng.2024.119743","url":null,"abstract":"<div><div>An adaptive fuzzy sliding mode control scheme based on data feedback is proposed in this paper, in order to achieve the trajectory tracking control of underactuated unmanned surface vehicles (USVs) in the present of unknown model parameters and environmental disturbances. Considering the problem of unknown model parameters, based on the feedback of sailing data, an online identification algorithm is designed to obtain real-time model parameters of USVs, which are used to establish the real-time simultaneous models of USV formation. A fuzzy control algorithm is introduced into the sliding mode controller design process to reduce convergence time and eliminate the chattering of the controller. Furthermore, a first-order low-pass filter is proposed to overcome the \"differential explosion\" issue, and a second-order differential tracker is designed to mitigate the jitter effects caused by higher-order derivatives of the lateral velocity. In addition, a nonlinear disturbance observer is developed to estimate and compensate the composite disturbances caused by real-time modeling inaccuracies and ocean environment disturbances. Finally, the effectiveness and robustness of the proposed control scheme are verified by several simulation experiment cases.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119743"},"PeriodicalIF":4.6,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.oceaneng.2024.119738
Solène Dealbera , Damien Sous
Friction dissipation induced by the seabed is a key factor for wave attenuation in nearshore environments presenting large roughness structures, such as rocky or coral shores. Two seminal models are classically used to predict bottom friction dissipation: the bottom stress (BS) and bulk canopy drag (BCD) models. Aiming to compare the performances of both models in controlled laboratory conditions, the present paper reanalyses the wave dissipation data provided by Dealbera et al., (2024). An approach to calculate the frontal transverse area based on real terrain consideration is suggested. The hydraulic parameter and the drag coefficient are optimized from the experimental data using several approaches and model parameterizations. Performance estimators of each model parameterization are compared and reveal a more robust predictive performance of the BCD model. The BS model could be improved by changing the vertical reference of the estimated flow velocity.
{"title":"Frictional wave dissipation in macro-roughness environments: A comparison of bottom stress and bulk canopy drag models","authors":"Solène Dealbera , Damien Sous","doi":"10.1016/j.oceaneng.2024.119738","DOIUrl":"10.1016/j.oceaneng.2024.119738","url":null,"abstract":"<div><div>Friction dissipation induced by the seabed is a key factor for wave attenuation in nearshore environments presenting large roughness structures, such as rocky or coral shores. Two seminal models are classically used to predict bottom friction dissipation: the bottom stress (BS) and bulk canopy drag (BCD) models. Aiming to compare the performances of both models in controlled laboratory conditions, the present paper reanalyses the wave dissipation data provided by Dealbera et al., (2024). An approach to calculate the frontal transverse area based on real terrain consideration is suggested. The hydraulic parameter and the drag coefficient are optimized from the experimental data using several approaches and model parameterizations. Performance estimators of each model parameterization are compared and reveal a more robust predictive performance of the BCD model. The BS model could be improved by changing the vertical reference of the estimated flow velocity.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119738"},"PeriodicalIF":4.6,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.oceaneng.2024.119760
Zheping Yan , Sijia Cai , Shuping Hou , Jinyu Yan
This paper presents a novel adaptive quantum multi-objective parrot optimizer (AQMOPO) for addressing the task allocation problem of searching an underwater region by a system comprising multiple unmanned underwater vehicles (UUVs). The three objectives for evaluating the effectiveness of this task allocation are the shortest moving path, the uniform task time, and the minimum number of turns in the search process, and these three objectives are competitive and incommensurable. The conventional parrot optimizer is applied to multi-objective optimization problems in accordance with the theory of non-dominated sorting. Furthermore, the solutions and parameters in AQMOPO are described in terms of quantum and updated by quantum computation to enhance the search performance of the algorithm, taking into account the coverage circles in the mission area. Subsequently, the adaptive strategy is employed to adjust the behaviors within the parrot optimizer, while the elite retention strategy is utilized to retain the most optimal solutions, thereby enhancing the efficacy of the algorithm. The results of the simulation demonstrate that the AQMOPO proposed in this paper is capable of implementing multi-objective task allocation for multi-UUV systems, thereby enabling them to complete searches in underwater complex areas.
{"title":"Adaptive quantum multi-objective parrot optimizer for task allocation of multi-UUV systems in underwater search","authors":"Zheping Yan , Sijia Cai , Shuping Hou , Jinyu Yan","doi":"10.1016/j.oceaneng.2024.119760","DOIUrl":"10.1016/j.oceaneng.2024.119760","url":null,"abstract":"<div><div>This paper presents a novel adaptive quantum multi-objective parrot optimizer (AQMOPO) for addressing the task allocation problem of searching an underwater region by a system comprising multiple unmanned underwater vehicles (UUVs). The three objectives for evaluating the effectiveness of this task allocation are the shortest moving path, the uniform task time, and the minimum number of turns in the search process, and these three objectives are competitive and incommensurable. The conventional parrot optimizer is applied to multi-objective optimization problems in accordance with the theory of non-dominated sorting. Furthermore, the solutions and parameters in AQMOPO are described in terms of quantum and updated by quantum computation to enhance the search performance of the algorithm, taking into account the coverage circles in the mission area. Subsequently, the adaptive strategy is employed to adjust the behaviors within the parrot optimizer, while the elite retention strategy is utilized to retain the most optimal solutions, thereby enhancing the efficacy of the algorithm. The results of the simulation demonstrate that the AQMOPO proposed in this paper is capable of implementing multi-objective task allocation for multi-UUV systems, thereby enabling them to complete searches in underwater complex areas.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119760"},"PeriodicalIF":4.6,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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