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Application of A* algorithm for real-time path re-planning of an unmanned surface vehicle avoiding underwater obstacles 总被引:1,自引:0,他引:1
Thanapong Phanthong Toshihiro Maki Tamaki Ura Takashi Sakamaki Pattara Aiyarak 《船舶与海洋工程学报》2014,13(1):105-116
This paper describes path re-planning techniques andunderwater obstacle avoidance for unmanned surface vehicle (USV)based on multi-beam forward looking sonar (FLS). Near-optimalpaths in static and dynamic environments with underwaterobstacles are computed using a numerical solution procedure basedon an A algorithm. The USV is modeled with a circular shape in 2degrees of freedom (surge and yaw). In this paper, two-dimensional(2-D) underwater obstacle avoidance and the robust real-time pathre-planning technique for actual USV using multi-beam FLS aredeveloped. Our real-time path re-planning algorithm has beentested to regenerate the optimal path for several updated frames inthe field of view of the sonar with a proper update frequency of theFLS. The performance of the proposed method was verifiedthrough simulations, and sea experiments. For simulations, theUSV model can avoid both a single stationary obstacle, multiplestationary obstacles and moving obstacles with the near-optimaltrajectory that are performed both in the vehicle and the worldreference frame. For sea experiments, the proposed method for anunderwater obstacle avoidance system is implemented with a USVtest platform. The actual USV is automatically controlled andsucceeded in its real-time avoidance against the stationary underseaobstacle in the field of view of the FLS together with the GlobalPositioning System (GPS) of the USV. 相似文献
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《船舶与海洋工程学报》2018,(4)
Robust and efficient AUV path planning is a key element for persistence AUV maneuvering in variable underwater environments. To develop such a path planning system, in this study, differential evolution(DE) algorithm is employed. The performance of the DE-based planner in generating time-efficient paths to direct the AUV from its initial conditions to the target of interest is investigated within a complexed 3D underwater environment incorporated with turbulent current vector fields, coastal area,islands, and static/dynamic obstacles. The results of simulations indicate the inherent efficiency of the DE-based path planner as it is capable of extracting feasible areas of a real map to determine the allowed spaces for the vehicle deployment while coping undesired current disturbances, exploiting desirable currents, and avoiding collision boundaries in directing the vehicle to its destination. The results are implementable for a realistic scenario and on-board real AUV as the DE planner satisfies all vehicular and environmental constraints while minimizing the travel time/distance, in a computationally efficient manner. 相似文献
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A path following control algorithm for an unmanned underwater vehicle(UUV) using temporary path generation guidance was proposed in this paper.Owing to different initial states of the vehicle,such as position and orientation,the path following control in the horizontal plane may yield a poor performance.To deal with the negative effect induced by initial states,a temporary path generation was presented based on the relationship between the original reference path and the vehicle’s initial states.With different relative positions between the vehicle and reference path,including out of straight lines,as well as inside and outside a circle,the related temporary paths guiding the vehicle to the reference path were able to be generated in real time.The vehicle was guided to steer along the temporary path until it reached the tangent point at the reference path,where the controller was designed using the input-output feedback linearization method.Simulation results demonstrated that the proposed algorithm is effective under the three different situations mentioned above. 相似文献
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《船舶与海洋工程学报》2021,(2)
There is much need for autonomous underwater vehicles(AUVs) for inspection and mapping purposes.Most conventional AUVs use torpedo-shaped single-rigid hull,because of which their manoeuvrability is limited.Moreover,any increase in payload results in a larger hull size and the turning diameter,limiting its operation in constrained areas.As a solution to this problem,we develop M-Hull,a subsurface mapping AUV with a modular-split hull design that provides better manoeuvrability than a conventional torpedo-shaped vehicle.At the same time,it has more agility than an unconventional bio-inspired snake-like vehicle though their designs look similar.This approach makes it a hybrid solution between conventional torpedo-shaped AUVs and unconventional bio-inspired vehicles.We focus on improving the turning diameter during the mapping operation,and hence this paper concentrates on the dynamic aspects of the 2 D turning motion of the vehicle.It will provide the relationship between turning speed,thrust,and joint torque requirements for the multi-hull underwater vehicle.Different turning modes are compared to choose an optimum turning configuration,and the critical speed is calculated for the vehicle's safe operation.In the end,the modelling is verified using the experimental data.One can follow the method followed here for the 2 D motion analysis of similar underwater vehicles. 相似文献
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Path optimization for marine vehicles in ocean currents using reinforcement learning 总被引:1,自引:0,他引:1
This study proposes a path planning algorithm for marine vehicles based on machine learning. The algorithm considers the dynamic characteristics of the vehicle and disturbance effects in ocean environments. The movements of marine vehicles are influenced by various physical disturbances in ocean environments, such as wind, waves, and currents. In the present study, the effects of ocean currents are the primary consideration. A kinematic model is used to incorporate the nonholonomic motion characteristics of a marine vehicle, and the reinforcement learning algorithm is used for path optimization to generate a feasible path that can be tracked by the vehicle. The proposed approach determines a near-optimal path that connects the start and goal points with a reasonable computational cost when the map and current field data are provided. To verify the optimality and validity of the proposed algorithm, a set of simulations were performed in simulated and actual ocean current conditions, and their results are presented. 相似文献
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《船舶与海洋工程学报》2015,(4)
Underwater terrain-aided navigation is used to complement the traditional inertial navigation employed by autonomous underwater vehicles during lengthy missions. It can provide fixed estimations by matching real-time depth data with a digital terrain map. This study presents the concept of using image processing techniques in the underwater terrain matching process. A traditional gray-scale histogram of an image is enriched by incorporation with spatial information in pixels. Edge corner pixels are then defined and used to construct an edge corner histogram, which employs as a template to scan the digital terrain map and estimate the fixes of the vehicle by searching the correlation peak. Simulations are performed to investigate the robustness of the proposed method, particularly in relation to its sensitivity to background noise, the scale of real-time images, and the travel direction of the vehicle. At an image resolution of 1 m~2/pixel, the accuracy of localization is more than 10 meters. 相似文献
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自主式水下机器人最优路径规划问题的研究 总被引:2,自引:0,他引:2
路径规划是水下机器人实现自主航行的重要环节。根据自主式水下机器人的动力学性质,路径规划的特点以及实现智能行为的要求,采用基于案例的遗传算法,实现了自主式水下机器人最优路径规划。给出该方案的基本框架和算法,在基于案例类比的学习方法中引入模糊多属性综合决策的方法建立决策算子进行案例的匹配,在遗传算法中实际知识的指导,适当地改进遗传算子,加快搜索速度。仿真结果证明该路径规划方法能够取得较好的规划结果,使自主式水下机器人具有了一定的自主导航,自主避障和自主作业的能力。 相似文献
11.
Nikolay Burlutskiy Yaniss Touahmi Beom Hee Lee 《Journal of Marine Science and Technology》2012,17(3):315-329
Autonomous underwater vehicles (AUVs) have rapidly developed in the last few decades due to their autonomous properties in the investigation of an underwater environment. The goal of this paper is to develop a power efficient formation control for the cooperative motion of AUVs with a support vessel as a leader. In this paper, a kinematic algorithm for the joint motion of an AUV with a support vessel was developed and that algorithm was expanded for the formation of AUVs. The AUV yaw, surge and sway control loops were designed for that purpose. The complexing navigation system structure for the AUV was also developed. Simulation results demonstrated efficiency of the proposed kinematic algorithm for the joint motion of AUVs. Also, influence of lateral ocean current was considered. After development of the centralized leader?Cfollower formation control for the group of AUVs with a support vessel as a leader, we optimized a formation configuration in terms of power efficiency. Drag forces caused by AUV motion in the water can significantly influence power consumption. We investigated the relationship between the AUV's formation configuration, underwater coverage efficiency, communication quality and power consumption. As a result of research, we proposed a power efficient formation configuration for typical underwater operations. As a result, the effect of the AUV formation configuration on the power consumption was investigated and a trade-off solution for the optimal AUV positions in formation with minimal energy consumption, high coverage efficiency and small communication power consumption was derived. 相似文献
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针对现有的离散生物启发神经网络(Glasius bioinspired neural networks, GBNN)算法在未知环境下,存在的路径规划时间长、易陷入局部最优等问题,提出一种结合A*与GBNN模型的改进算法。在GBNN活性值栅格网络中,算法将各栅格的活性值作为A*的代价函数进行运算并使用跳点搜索规则优化,实现未知环境下的实时路径规划。仿真实验结果表明,该算法有效改善了自主水下航行器在未知环境下的寻路效率,可以满足自主水下航行器实时路径规划需求。 相似文献
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An autonomous underwater vehicle (AUV) must use an algorithm to plan its path to distant, mobile offshore objects. Because
of the uneven distribution of obstacles in the real world, the efficiency of the algorithm decreases if the global environment
is represented by regular grids with all of them at the highest resolution. The framed quadtree data structure is able to
more efficiently represent the environment. When planning the path, the dynamic object is expressed instead as several static
objects which are used by the path planner to update the path. By taking account of the characteristics of the framed quadtree,
objects can be projected on the frame nodes to increase the precision of the path. Analysis and simulations showed the proposed
planner could increase efficiency while improving the ability of the AUV to follow an object. 相似文献
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水下拖曳系统水动力特性的计算流体力学分析 总被引:1,自引:0,他引:1
提出了一种新型的水下拖曳系统三维水动力数学模型。在该模型中拖曳缆绳的控制方程由Ablow andSchechter模型给出,Gertler and Hargen的水下运载体六自由度运动方程被用来描述拖曳体的水动力状态。通过对拖曳缆绳和拖曳体的控制方程在连接点处进行边界条件耦合,从而构成整个拖曳系统的水动力数学模型。在研究中,拖曳系统的水动力数学模型通过时间与空间的中心差分方程来逼近,每一时刻拖曳体所受的水动力通过求解Navier-Stokes方程得到。所提出的模型特别适用于拖曳体为非回转体、非流线型的主体,或必须考虑拖曳体各组成部分的水动力相互影响的情况。计算结果与相应的实验室样机试验结果的比较表明,所提出的模型可以有效地预报拖曳系统的水动力特性。利用所提出的水动力模型,对华南理工大学提出的自主稳定可控制水下拖曳体在实际海况下的数值模拟结果显示,所分析的拖曳体具有良好的运动与姿态稳定性,是一种值得开发研究的新型水下拖曳体。 相似文献
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Valuable mineral resources are widely distributed throughout the seabed. autonomous underwater vehicles (AUVs) are preferable
to remotely-operated vehicles (ROVs) when probing for such mineral resources as the extensive exploration area makes it difficult
to maintain contact with operators. AUVs depend on batteries, so their power consumption should be reduced to extend exploration
time. Power for conventional marine instrument systems is incorporated in their waterproof sealing. External intermittent
control of this power source until termination of exploration is challenging due to limitations imposed by the underwater
environment. Thus, the AUV must have a power control system that can improve performance and maximize use of battery capacity.
The authors developed such a power control system with a three-step algorithm. It automatically detects underwater operational
states and can limit power, effectively decreasing power consumption by about 15%. 相似文献