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This paper presents a probabilistic approach to estimate the collision risk between two ROVs operating on trajectories at different depth levels. For an analytically tractable formulation, a circular cylindrical boundary is considered as a safe separation zone around each ROV, and any violation of this safe zone is defined as a conflict. The conflict probability between two ROVs is then estimated...
Acoustic source localization is one of the most essential problems for acoustic based navigation of underwater vehicle. For this purpose, this paper addresses three dimensional acoustic source localization in underwater environment. TDOA based localization using multiple hydrophones is used. A simplified configuration of four hydrophones is used to acquire analytic solution of source localization...
This paper describes a method for detection of object using 3D point cloud measurement in the sea environment. The method employs RBNN clustering method and using a 3D Lidar, mono-vision and stereo-vision cameras, and radar vision system. A radially based nearest neighbors (RBNN) clustering technique is adopted to perform object detection on 3D point cloud clustering. RBNN is constructing clusters...
This paper explores the effectiveness of MOOS-IvP middleware for Unmanned Surface Vehicles(USV). As unmanned technology evolves, various functions are required to carry out some missions. Also, as the USVs have more sensors, the complexity of data sharing is increasing. A good solution to deal with this is middleware. The MOOS-IvP is a C++ based open source publish-subscribe middleware. It consists...
For the underwater search task, imaging sonar is very useful equipment to obtain the visual data of the underwater environment. Generally, the search range of imaging sonar depends on the frequency of the sound. High-frequency imaging sonar is suitable to search near area within 5m and low-frequency is able to search the area between 5m to 100m. In this paper, we presents experimental results of landmarks...
Autonomous underwater vehicles (AUVs) are usually equipped with one or more optical cameras to obtain visual data of underwater environments. The camera can also be used to estimate the AUV's pose information, along with various navigation sensors such as inertial measurement unit (IMU), Doppler velocity log (DVL), depth sensor, and so on. In this paper, we propose a vision-based simultaneous localization...
Underwater harbor structures should be inspected regularly for safety problem. Conventional inspection methods which are performed by divers have several limitations including safety and health problem of divers. This paper presents development of a ROV and experimental results for visual inspection of harbor structures. The ROV is equipped with visual systems for inspection tasks, navigation system...
Recently Korea Research Institute of Ships and Ocean Engineering has developed an underwater sound transmission system (USTS) for a light-work class ROV. Its main purposes are not only to measure underwater sound using two hydrophones and replay it for ROV operators on the surface vessel but also to identify source direction. The subsea unit of the system is composed of amplifiers, filters, an ADC,...
Autonomous underwater vehicles (AUVs) can perform flexible operations in complex underwater environments due to their autonomy. Localization is one of the key components of autonomous navigation. Since the inertial navigation system of an AUV suffers from drift, observing fixed objects in an inertial reference system can enhance the localization performance. In this paper, we propose a method of localizing...
This paper proposes a method for fused navigation of an unmanned marine surface vehicle (UMSV). The method also detects the outlier and interference of global positioning system (GPS) simultaneously. The method fuses available sensor measurements through extended Kalman filter (EKF) to find the location and attitude of the vehicle. The method uses error covariance of estimated location for detection...
In this paper, we propose a method of AUV localization and mapping using visual measurement of underwater structures. Since the inertial navigation system (INS) of AUV suffers from drift, visual observation of fixed objects can enhance the localization performance. In a framework of pose graph optimization, depth map estimation of underwater structures and tracing of AUV trajectory are concurrently...
Development of localization method is crucial for underwater vehicles to navigate in underwater environments. This paper presents a method of localization for underwater vehicles using acoustic signal. Artificial underwater acoustic sources are used as landmarks in underwater environment and underwater vehicle performs localization by acquiring acoustic signals transmitted from the sources. TDOA based...
This paper proposes a method for fused navigation of an unmanned surface vehicle (USV). The method also detects the outlier and interference of global positioning system (GPS) simultaneously. The method fuses available sensor measurements through extended Kalman filter (EKF) to find the location and attitude of the USV. The method uses error covariance of estimated location for detection of GPS outlier...
This paper presents the bundle adjustment (BA) between a sonar and optical image for an Opti-Acoustic sensor model. An Opti-Acoustic sensor model allows heterogeneous sensor fusion of an optical camera and acoustic sonar that have a mutual supplementary relation. There are two challenges to the Opti-Acoustic method. First, it is difficult to guarantee a common view from the two significantly different...
Recently, a number of unmanned surface vehicles (USVs) have been developed and researched for various fields such as military, environment and robotics. These vehicles are used as an application platform of diverse algorithms. This paper introduces a development of a multi-purpose USV “eVe-1”. Also, several path tracking methods are compared by using simulation. The hardware of “eVe-1” is designed...
This paper presents a method of topological modeling for marine environment. The proposed method detects landmarks from underwater and above-water environment. The topological model is acquired by applying Delaunay triangulation to the detected landmarks. Nodes are defined as triangulated region of Delaunay triangulation and edges represent adjacency between two nodes. The proposed method constructs...
In this paper, we propose a method of AUV localization and mapping using visual measurement of underwater structures. Since the inertial navigation system (INS) of AUV suffers from drift, observing fixed objects can enhance the localization performance. Depth map estimation of underwater structures and tracking of an AUV are complementarily handled in a framework of pose graph optimization. Estimation...
This paper proposes a method for attitude estimation that utilizes the depth measurement as well as the MEMS-AHRS (Micro-electromechanical systems Attitude Heading Reference System). Estimating attitude in real-time is crucial for navigation of an unmanned underwater vehicle since path planning, trajectory tracking, and collision-avoidance is based on the attitude information. Many of the attitude...
This paper describes the implementation of precise underwater navigation system using multiple sensor fusion technique using low cost navigation sensors. Estimation of accurate positions and attitudes is a key issue to achieve qualified mapping results. To implement the precise underwater navigation for qualified mapping solutions, three strategies are selected. Firstly, sensor alignment is conducted...
This paper presents experimental results of a real-time sonar-based localization technique using the probability-based landmark-recognition method. Sonar based localization is used for the navigation of unmanned underwater vehicle (UUVs). Inertial sensors such as inertial measurement unitss (IMUs), doppler velocisy logs (DVLs), and external information obtained from sonar are combined using the extended...
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