Classification of Sailboat Tell Tail Based on Deep Learning

The tell tail is usually placed on the triangular sail to display the running state of the air flow on the sail surface.It is of great significance to make accurate judgement on the drift of the tell tail of the sailboat during sailing for the best sailing effect.Normally it is difficult for sailors to keep an eye for a long time on the tell sail for accurate judging its changes,affected by strong sunlight and visual fatigue.In this case,we adopt computer vision technology in hope of helping the sailors judge the changes of the tell tail in ease with ease.This paper proposes for the first time a method to classify sailboat tell tails based on deep learning and an expert guidance system,supported by a sailboat tell tail classification data set on the expert guidance system of interpreting the tell tails states in different sea wind conditions,including the feature extraction performance.Considering the expression capabilities that vary with the computational features in different visual tasks,the paper focuses on five tell tail computing features,which are recoded by an automatic encoder and classified by a SVM classifier.All experimental samples were randomly divided into five groups,and four groups were selected from each group as the training set to train the classifier.The remaining one group was used as the test set for testing.The highest resolution value of the ResNet network was 80.26%.To achieve better operational results on the basis of deep computing features obtained through the ResNet network in the experiments.The method can be used to assist the sailors in making better judgement about the tell tail changes during sailing.

Analysis of Influencing Factors on Lift Coefficients of Autonomous Sailboat Double Sail Propulsion System Based on Vortex Panel Method

Sail is the core part of autonomous sailboat and wing sail is a new type of sail. Wing sail generates not only propulsion but also lateral force and heeling moment. The latter two will affect the navigation status and bring resistance. Double sail can effectively reduce the center of wind pressure and heeling moment. In order to study the effect of distance between two sails, airfoil and attack angle on the total lift coefficient of double sail propulsion system, pressure coefficient distribution and lift coefficient calculation model have been established based on vortex panel method. By using the basic finite solution, the fluid dynamic forces on the two-dimensional sails are computed.The results show that, the distance in the range of 0 to 1 time chord length, when using the same airfoil in the fore and aft sail, the total lift coefficient of the double sail increases with the increase of distance, finally reaches a stable value in the range of one to three times chord length. Lift coefficients of thicker airfoils are more sensitive to the change of distance. The thicker the airfoil, the longer distance is required of the total lift coefficient toward stable.When different airfoils are adopted in fore and aft sail, the total lift coefficient increases with the increase of the thickness of aft sail. The smaller the thickness difference is, the more sensitive to the distance change the lift coefficient is. The thinner the fore sail is, the lower the influence will be on the lift coefficient of aft sail.

Influence of Autonomous Sailboat Dual-Wing Sail Interaction on Lift Coefficients

To analyze the influence of the chord length ratio and angle of attack on lift coefficients and explore the interaction mechanism between the two,we established a calculation model of the pressure distribution coefficient on the airfoil surface and lift coefficient of a dual-wing sail on the basis of the vortex panel method.Computational fluid dynamics was used in auxiliary calculation and analysis.Results revealed a reciprocal interference between the front-wing and rear-wing sails.The total lift coefficient of the dual-sail increased with an increase in the front sail chord length.The lift coefficient of the rear sail decreased with an increase in the front sail chord length or angle of attack.The front sail wake affected the pressure distribution on the upper and lower surfaces of the rear sail leading edge.

Path Planning and Navigation of Oceanic Autonomous Sailboats and Vessels: A Survey

Oceanic autonomous surface vehicles(ASVs) are one kind of autonomous marine robots that have advantages of energy saving and is flexible to use. Nowadays, ASVs are playing an important role in marine science, maritime industry, and national defense. It could improve the efficiency of oceanic data collection, ensure marine transportation safety, and protect national security. One of the core challenges for ASVs is how to plan a safe navigation autonomously under the complicated ocean environment. Based on the type of marine vehicles, ASVs could be divided into two categories: autonomous sailboats and autonomous vessels. In this article, we review the challenges and related solutions of ASVs' autonomous navigation, including modeling analysis, path planning and implementation. Finally, we make a summary of all of those in four tables and discuss about the future research directions.

Sailboat navigation control system based on spiking neural networks

In this paper,we presented the development of a navigation control system for a sailboat based on spiking neural networks(SNN).Our inspiration for this choice of network lies in their potential to achieve fast and low-energy computing on specialized hardware.To train our system,we use the modulated spike time-dependent plasticity reinforcement learning rule and a simulation environment based on the BindsNET library and USVSim simulator.Our objective was to develop a spiking neural network-based control systems that can learn policies allowing sailboats to navigate between two points by following a straight line or performing tacking and gybing strategies,depending on the sailing scenario conditions.We presented the mathematical definition of the problem,the operation scheme of the simulation environment,the spiking neural network controllers,and the control strategy used.As a result,we obtained 425 SNN-based controllers that completed the proposed navigation task,indicating that the simulation environment and the implemented control strategy work effectively.Finally,we compare the behavior of our best controller with other algorithms and present some possible strategies to improve its performance.

Finite-time path following control of a sailboat with actuator failure and unknown sideslip angle

Suffering from actuator failure and complex sideslip angle,the motion control of a sailboat becomes challenging.In this paper,an improved double finite-time observer-based line-of-sight guidance and finite-time control(IDFLOS-FC)scheme is presented for path following of sailboats.The salient features of the proposed IDFLOS-FC scheme are as follows:(1)Considering the problem of actuator failure,an actuator failure model is introduced into the dynamics model of a sailboat.(2)The time-varying sideslip angle of the sailboat is accurately observed by the double finite-time sideslip observers(DFSOs),which reduces the error in line-of-sight(LOS)guidance.(3)A radial basis function(RBF)neural network is used to fit the uncertainty of the model,and the upper bound of the sum of fault effects and external disturbances is estimated based on adaptive theory,so that the controller has accurate tracking and interference suppression.(4)According to the Lyapunov method,the system is finite-time stable.Finally,simulation was used to validate the effectiveness of the method.

激光雷迪尔级帆船水动力特性试验与数值计算研究

采用试验观测和数值计算的方法研究了六自由度激光雷迪尔级帆船的水动力特性.设计了一套帆船六元力试验测量方法,通过拖曳水池试验获得帆船的水动力特性.采用雷诺时均计算方法和重叠网格技术,通过对试验和仿真的六元力结果进行对比,验证了数值计算方法的准确性.对不同航行姿态下的帆船水动力性能进行了模拟,分析了船体航速、迎角、侧倾角、漂角四个因素对帆船六元水动力的影响规律.研究结果表明:对纵向力影响权重较高的因子是航速和迎角,纵向力与航速呈非线性关系;对横向力影响较大的因子是漂角且两者呈线性关系;侧倾力矩主要受侧倾角和漂角的影响,随侧倾角的增加先减小后增大,在侧倾角为15°附近出现拐点;俯仰力矩受航速和迎角影响较大,随迎角的增大呈线性增大关系;转首力矩对漂角变化响应最大,随漂角增大线性增大.文中获得的六元水动力特性和数据可为提高帆船的操纵性提供重要数据支撑.

社会转型视野中的湖南木帆船运输业探析(1949—1952)

1949—1952年是国民经济恢复时期,社会急剧变革,各行业在新民主主义经济秩序下重建和发展。木帆船运输市场得以重建,成为当时重要的运输力量。以湖南为例,新中国成立后,木帆船运输业逐渐恢复,建立了新民主主义的运输市场秩序;降低运价,加强管理,在城乡物资交流中发挥着民船联运的优势,大运输体系建立起来;土产、矿产和粮食得以外运,工业品和食盐输往农村,农村初级市场末端得以拓展,新商业路线得到开辟,在国家工程建设中发挥着重要作用。

基于模型预测控制的无人帆船轨迹跟踪方法

[目的]面向无人帆船在水面、水下跨域异构海洋机器人的协同作业场景,提出基于模型预测控制(MPC)的无人帆船轨迹跟踪方法。[方法]针对“海鸥”号无人帆船,建立其动力学模型及运动学模型,通过分析无人帆船动力学特点及执行器约束条件,构建MPC目标函数及系统约束条件,将无人帆船的轨迹跟踪问题转化为优化问题,并利用Matlab软件开展仿真实验验证。[结果]仿真结果表明,与“帆–舵”分离的PID轨迹跟踪控制方法相比,所提出的无人帆船“帆–舵”联合MPC控制方法更便于添加约束条件,其在风向变化的情况下能以更小的轨迹跟踪误差来更快地收敛于指定轨迹,且其可以实现逆风折线航行。[结论]研究成果可为无人帆船的帆、舵控制提供新的思路,提高其轨迹跟踪能力,进一步为无人帆船与AUV的高效协同作业提供技术保障。

基于数据融合的无人帆船真风计算方法

针对无人帆船真风获取困难且所用风传感器受帆船姿态影响的问题,提出了一种基于姿态信息、相对风和航行风融合的无人帆船真风计算方法。首先利用姿态仪获得帆船的俯仰角和横滚角,通过空间坐标旋转变换矫正相对风测量结果;其次利用卡尔曼滤波算法对航行风和矫正后的相对风进行滤波;最后利用扩展卡尔曼滤波进行真风融合计算。实验证明,该方法能够有效抑制帆船运动对风测量的影响,准确提取真风风速和风向,满足无人帆船航行控制需求。

风帆构型波浪滑翔器局部路径规划研究

风帆构型波浪滑翔器(sailboat architecture wave glider,SWG)是一种新型单体式欠驱动海洋观测平台。相较于传统波浪滑翔器,风帆构型波浪滑翔器以海洋可再生能源——风能与波浪能为动力,克服了机动性能弱和抗流能力差等缺点,有效实现持续动能转换,执行面向大范围海域快速巡航等任务。考虑到风帆构型波浪滑翔器对风场环境的依赖性,传统路径规划方法对风帆构型波浪滑翔器的适用性很低,因此提出了一种适用于风帆构型波浪滑翔器在风场环境下的局部路径规划算法。所提算法通过改进引力势场与斥力势场,克服了传统人工势场算法中机器人无法到达靠近障碍物的目标点和碰撞远离目标点的障碍物的缺陷。所提算法引入一种风势场,使所提算法针对不同风场规划出不同的路径,并且规划路径满足风帆构型波浪滑翔器的运动学约束。最后通过MATLAB仿真和海试实验,验证了所提出的局部路径规划算法对风帆构型波浪滑翔器的适用性。

无人帆船柔性风帆性能的流固耦合仿真分析

为了探究柔性风帆在不同风况下的变形结果及变形对气动性能的影响,本研究中进行柔性风帆性能的流固耦合仿真分析:构建1.4 m无人帆船主帆初始形状模型和材料模型,并基于LS-DYNA程序对柔性风帆在不同攻角下进行变形计算,构建变形后的风帆形状;基于STAR CCM+程序在相同条件下对变形风帆和初始风帆进行气动性能计算。结果表明:柔性风帆变形结果主要表现为拱度变化和有效攻角变化,材料本身的拉伸对拱度变化的影响可以忽略不计;当拱度增大带来的升力增大效应强于有效攻角减小带来的升力减小效应时,升力总体上为增大;变形风帆的升力系数随着攻角的变化而更为合理、升阻更大;根据变形风帆的极曲线,获得不同航向角下的最佳攻角和最大推力系数,适用于优化柔性风帆无人帆船横风航行时的控帆策略。

马格努斯圆柱及变角度襟翼对无人帆船气动性能的影响

[目的]旨在研究马格努斯翼型和变角度襟翼对无人帆船气动性能的影响及其优化,以提高无人帆船的航行效率。[方法]采用CFD方法,以NACA 0021翼型作为无人帆船主翼帆的基准翼型,在主翼帆顶缘耦合马格努斯圆柱,分析马格努斯圆柱关键参数(直径、位置和间隔)对翼型升阻特性的影响规律;在主翼帆顶缘耦合马格努斯圆柱的基础上,将襟翼帆嵌入主翼帆尾缘,研究不同襟翼帆偏转角下翼型周围流场和升阻特性及其对无人帆船推力性能的影响规律。[结果]结果表明:在大攻角下,马格努斯圆柱对翼型气动性能具有提升作用,在所研究参数范围内翼型升阻比与马格努斯圆柱位置正相关,与马格努斯圆柱直径和间隔负相关,其中圆柱的直径和间隔对翼型气动性能影响较大,位置的影响最小;在小攻角下,变角度襟翼帆对翼型气动性能的提升更明显,在0°~15°攻角内,翼型的升阻比与襟翼帆偏转角正相关;在马格努斯圆柱及襟翼帆共同作用下,风帆推力系数最大提升27%,且与襟翼帆的偏转角正相关。[结论]研究结果可为马格努斯圆柱及嵌入式襟翼帆在无人帆船领域的应用提供参考。

无人帆船翼帆桅杆根部应力影响因素及其影响规律研究

为研究翼帆桅杆根部应力的影响因素及其影响规律,基于等效原理提出了桅杆根部应力的数值计算模型,并通过有限元计算验证了所提模型的准确性。基于所建模型推导发现,对桅杆根部应力造成影响的参数共包含4个外部参数(无人帆船横摇周期、横摇幅值、横摇角度、翼帆偏转角度)和3个翼帆本体参数(翼帆重心高度、翼帆质量、偏心距离)。基于所建模型分析了上述因素对桅杆根部应力的影响规律,发现应力值与横摇周期成递减的负二次幂函数关系,与横摇幅值、翼帆重心高度、偏心距离和翼帆质量成正比,应力值随偏转角度的变化曲线与正弦曲线相吻合,并且在一个横摇周期内应力值曲线呈现正弦波形。最后,针对应力集中于桅杆根部的情况,提出了一种设置加强筋以优化结构的方法,并通过有限元计算和转台晃动实验分析的方法进行了验证,发现所提方法可以有效减小翼帆桅杆工作过程中根部的应力值。

基于改进自适应蚁群算法的无人帆船路径规划

针对特定环境下的无人帆船路径规划问题,考虑到无人帆船复杂运动特性及目前路径评价指标较为单一等问题,本文提出了一种基于改进自适应蚁群算法的无人帆船路径规划方法。通过对角线优先规则解决蚁群前期寻路的盲目性问题,加快最优路径收敛速度;结合无人帆船在特定风向风速下的航速大小设计启发函数,并在转移概率中增加目标终点对无人帆船的吸引作用,使无人帆船最优路径评价指标更加贴合实际应用;引进不同自适应调整策略分别改进蚁群算法信息素更新机制和搜索步长,达到平衡全局搜索和局部搜索的目的,有效避免无人帆船路径陷入局部最优。本文通过多组仿真对比实验,验证了所提算法的合理性与优越性。

基于海洋机器人的科学观测与实验系统研究现状与展望

海洋机器人具有观测范围大、作业灵活、机动性好、可控性强等突出优点,在海洋科学观测与海洋科学实验中发挥了重要作用,促进了物理海洋和海洋生物地球化学的发展。为阐明海洋机器人在海洋科学观测和实验中的应用情况,以水下滑翔机、自主水下机器人(Autonomous Underwater Vehicle,AUV)和无人帆船3种典型的观测型海洋机器人为例介绍了海洋机器人在海洋科学观测中的应用现状;以原位采样与固定、原位培养与分析海洋机器人为例介绍了海洋机器人在海洋科学实验中的应用现状;最后结合未来海洋科学研究需求,从需求牵引的角度对基于机器人的科学观测与实验系统的发展趋势进行了展望。

帆船用缆绳的应用现状

缆绳在帆船运行中发挥着重要作用。缆绳的功能不同,其在选材、编织方法等方面亦有不同。简介了帆船用缆绳的材料、结构,并基于3种帆船用缆绳--控帆索、动力绳及捆帆绳介绍了它们的应用,为帆船用缆绳的后续开发提供支撑和新思路。

帆船直线航行比赛最优路径动态规划方法研究

针对帆船直线航行比赛的赛场情况,提出一种基于模糊综合评价和动态规划理论的帆船直航训练最优路径动态规划方法.首先以模糊逻辑为基础,建立帆船相对于目标点的隶属函数,并以此描述帆船的当前位置和方向信息;然后综合考虑行驶速度和接近目标点两个因素,建立综合评价函数,并以航道宽度为限制条件,利用动态规划原理分阶段进行航向决策.最后通过仿真验证了算法的有效性.

我国产学研合作动力机制研究

认为动力机制在很大程度上影响产学研合作的效果,通过分析影响企业、高等院校和科研院所合作的动力因素和阻力因素,提出了一种产学研合作的帆船动力机制模型。运用该模型深入研究了我国产学研合作的动力机制,并指出产学研合作应充分认识"合力"的重要性,通过"聚力"、"借力"和"避力"来提升产学研合作效果的政策性结论。

基于模糊综合评价的帆船行驶最优路径规划方法

路径规划是帆船比赛取胜的重要环节。综合栅格法和模糊概念,提出了基于模糊综合评价的帆船行驶最优路径规划方法。该方法采用栅格法建立帆船航行的二维平面信息,以模糊逻辑为基础,结合帆船的运动信息建立帆船在运动平面上的二维隶属函数模型,并采用模糊综合评价思想,综合考虑行驶速度和接近目标2个因素建立综合评价函数,进行行驶方向决策。利用宽度优先搜索算法实现全局最优路径搜索。仿真结果证明,该路径规划方法能够取得较好的规划结果,对指导帆船运动员进行科学训练有很好的应用价值。