Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study,with a 3D computational fluid dynami...Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study,with a 3D computational fluid dynamics package,which includes the immersed boundary method and the volume of fluid method,the adaptive multi-grid finite volume method,and the control strategy of fish swimming.Firstly,the mechanism of 3D fish swimming was studied and the vorticity dynamics root was traced to the moving body surface by using the boundary vorticity-flux theory.With the change of swimming speed,the contributions of the fish body and caudal fin to thrust are analyzed quantitatively.The relationship between vortex structures of fish swimming and the forces exerted on the fish body are also given in this paper.Finally,the 3D wake structure of self-propelled swimming of 3D bionic fish is presented.The in-depth analysis of the 3D vortex structure in the role of 3D biomimetic fish swimming is also performed.展开更多
Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried out. This is done with the assistance of a parallel software package produced for 3D m...Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried out. This is done with the assistance of a parallel software package produced for 3D moving boundary problems. This computational fluid dynamics package combines the adaptive multi-grid finite volume method, the immersed boundary method and VOF (volume of fluid) method. By using the package results of the self-propelled swimming of a 3D bionic fish and fish school in a vis- cous fluid are obtained. With comparison to the existing experimental measurements of living fishes, the predicted structure of vortical wakes is in good agreement with the measurements.展开更多
There are many kinds of swimming mode in the fish world, and we investigated two of them, used by cyprinids and bulltrout. In this paper we track the locomotion locus by marks in different flow velocity from 0.2 m...There are many kinds of swimming mode in the fish world, and we investigated two of them, used by cyprinids and bulltrout. In this paper we track the locomotion locus by marks in different flow velocity from 0.2 m·s^-1 to 0.8 m·s^-1. By fit the data above we could find out the locomotion mechanism of the two kinds of fish and generate a mathematical model of fish kine- matics. The cyprinid fish has a greater oscillation period and amplitude compared with the bulltrout, and the bulltrout changes velocity mainly by controlling frequency of oscillation.展开更多
Fishes have learned how to achieve outstanding swimming performance through the evolution of hundreds of millions of years,which can provide bio-inspiration for robotic fish design.The premise of designing an excellen...Fishes have learned how to achieve outstanding swimming performance through the evolution of hundreds of millions of years,which can provide bio-inspiration for robotic fish design.The premise of designing an excellent robotic fish include fully understanding of fish locomotion mechanism and grasp of the advanced control strategy in robot domain.In this paper,the research development on fish swimming is presented,aiming to offer a reference for the later research.First,the research methods including experimental methods and simulation methods are detailed.Then the current research directions including fish locomotion mechanism,structure and function research and bionic robotic fish are outlined.Fish locomotion mechanism is discussed from three views:macroscopic view to find a unified principle,microscopic view to include muscle activity and intermediate view to study the behaviors of single fish and fish school.Structure and function research is mainly concentrated from three aspects:fin research,lateral line system and body stiffness.Bionic robotic fish research focuses on actuation,materials and motion control.The paper concludes with the future trend that curvature control,machine learning and multiple robotic fish system will play a more important role in this field.Overall,the intensive and comprehensive research on fish swimming will decrease the gap between robotic fish and real fish and contribute to the broad application prospect of robotic fish.展开更多
计算流体力学是研究仿生机器鱼水动力特性的重要数值模拟方法,已在仿生学及海洋学等众多领域得到广泛应用。本文利用CNKI中文数据库及Web of Science核心合集数据库分别检索到201篇中文文献和146篇英文文献,运用Cite Space软件的文献计...计算流体力学是研究仿生机器鱼水动力特性的重要数值模拟方法,已在仿生学及海洋学等众多领域得到广泛应用。本文利用CNKI中文数据库及Web of Science核心合集数据库分别检索到201篇中文文献和146篇英文文献,运用Cite Space软件的文献计量学分析方法,对文献类型、期刊分布、发文量趋势、作者、研究机构和高被引文献进行了系统分析,并结合关键词网络知识图谱、关键词聚类图谱,探讨了计算流体力学在仿生机器鱼领域中的应用研究热点。结果表明:仿生机器鱼领域中外文献发文量呈现逐年上升趋势,且仿生类期刊及文献具有较高的影响因子与被引频次;研究学科领域涉及工程学、机器人学、力学与材料科学等多个交叉性学科;该领域内研究热点与重点方向为动力学模型、三维流场仿真、设计与制作。针对现有研究的不足,建议未来研究应深入探讨水生生物集群运动仿真、鱼类侧线感知机制和仿生机器鱼水动力试验,以期促进多学科融合,为仿生机器鱼的发展提供科学参考。展开更多
为满足仿生机器鱼目标检测的需要,在YOLOv5基础上提出了一种轻量级检测算法,降低算法复杂度并提高精度。首先对YOLOv5s模型进行改进,通过GhostConv和C3Ghost模块降低参数量和计算量。其次,引入CA和CoordConv模块增强特征提取和目标位置...为满足仿生机器鱼目标检测的需要,在YOLOv5基础上提出了一种轻量级检测算法,降低算法复杂度并提高精度。首先对YOLOv5s模型进行改进,通过GhostConv和C3Ghost模块降低参数量和计算量。其次,引入CA和CoordConv模块增强特征提取和目标位置感知能力,采用soft NMS减少使用传统非极大抑制(Non maximum suppression,NMS)带来的漏检、误检,同时使用MPDIoU简化相似性比较,提升检测精度和召回率。最后,所提出方法在目标检测数据集上的试验结果表明,改进的YOLOv5网络体积更小、精度更高,证明了该算法的有效性和优越性。展开更多
基金the support of National Natural Science Foundation of China (Grant No.10672183)
文摘Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study,with a 3D computational fluid dynamics package,which includes the immersed boundary method and the volume of fluid method,the adaptive multi-grid finite volume method,and the control strategy of fish swimming.Firstly,the mechanism of 3D fish swimming was studied and the vorticity dynamics root was traced to the moving body surface by using the boundary vorticity-flux theory.With the change of swimming speed,the contributions of the fish body and caudal fin to thrust are analyzed quantitatively.The relationship between vortex structures of fish swimming and the forces exerted on the fish body are also given in this paper.Finally,the 3D wake structure of self-propelled swimming of 3D bionic fish is presented.The in-depth analysis of the 3D vortex structure in the role of 3D biomimetic fish swimming is also performed.
基金Supported by the Key Project of National Natural Science Foundation of China (Grant No. 10532040)
文摘Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried out. This is done with the assistance of a parallel software package produced for 3D moving boundary problems. This computational fluid dynamics package combines the adaptive multi-grid finite volume method, the immersed boundary method and VOF (volume of fluid) method. By using the package results of the self-propelled swimming of a 3D bionic fish and fish school in a vis- cous fluid are obtained. With comparison to the existing experimental measurements of living fishes, the predicted structure of vortical wakes is in good agreement with the measurements.
基金the National Natural Science Foundation of China (Grant No. 50579007)
文摘There are many kinds of swimming mode in the fish world, and we investigated two of them, used by cyprinids and bulltrout. In this paper we track the locomotion locus by marks in different flow velocity from 0.2 m·s^-1 to 0.8 m·s^-1. By fit the data above we could find out the locomotion mechanism of the two kinds of fish and generate a mathematical model of fish kine- matics. The cyprinid fish has a greater oscillation period and amplitude compared with the bulltrout, and the bulltrout changes velocity mainly by controlling frequency of oscillation.
基金National Natural Science Foundation of China(Grant No.51275127).
文摘Fishes have learned how to achieve outstanding swimming performance through the evolution of hundreds of millions of years,which can provide bio-inspiration for robotic fish design.The premise of designing an excellent robotic fish include fully understanding of fish locomotion mechanism and grasp of the advanced control strategy in robot domain.In this paper,the research development on fish swimming is presented,aiming to offer a reference for the later research.First,the research methods including experimental methods and simulation methods are detailed.Then the current research directions including fish locomotion mechanism,structure and function research and bionic robotic fish are outlined.Fish locomotion mechanism is discussed from three views:macroscopic view to find a unified principle,microscopic view to include muscle activity and intermediate view to study the behaviors of single fish and fish school.Structure and function research is mainly concentrated from three aspects:fin research,lateral line system and body stiffness.Bionic robotic fish research focuses on actuation,materials and motion control.The paper concludes with the future trend that curvature control,machine learning and multiple robotic fish system will play a more important role in this field.Overall,the intensive and comprehensive research on fish swimming will decrease the gap between robotic fish and real fish and contribute to the broad application prospect of robotic fish.
文摘计算流体力学是研究仿生机器鱼水动力特性的重要数值模拟方法,已在仿生学及海洋学等众多领域得到广泛应用。本文利用CNKI中文数据库及Web of Science核心合集数据库分别检索到201篇中文文献和146篇英文文献,运用Cite Space软件的文献计量学分析方法,对文献类型、期刊分布、发文量趋势、作者、研究机构和高被引文献进行了系统分析,并结合关键词网络知识图谱、关键词聚类图谱,探讨了计算流体力学在仿生机器鱼领域中的应用研究热点。结果表明:仿生机器鱼领域中外文献发文量呈现逐年上升趋势,且仿生类期刊及文献具有较高的影响因子与被引频次;研究学科领域涉及工程学、机器人学、力学与材料科学等多个交叉性学科;该领域内研究热点与重点方向为动力学模型、三维流场仿真、设计与制作。针对现有研究的不足,建议未来研究应深入探讨水生生物集群运动仿真、鱼类侧线感知机制和仿生机器鱼水动力试验,以期促进多学科融合,为仿生机器鱼的发展提供科学参考。
文摘为满足仿生机器鱼目标检测的需要,在YOLOv5基础上提出了一种轻量级检测算法,降低算法复杂度并提高精度。首先对YOLOv5s模型进行改进,通过GhostConv和C3Ghost模块降低参数量和计算量。其次,引入CA和CoordConv模块增强特征提取和目标位置感知能力,采用soft NMS减少使用传统非极大抑制(Non maximum suppression,NMS)带来的漏检、误检,同时使用MPDIoU简化相似性比较,提升检测精度和召回率。最后,所提出方法在目标检测数据集上的试验结果表明,改进的YOLOv5网络体积更小、精度更高,证明了该算法的有效性和优越性。
