• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.575-582
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• 2014

In this paper, a simulation model for 7-phase BLDC motor drives for an Autonomous Underwater Vehicles (AUV) is proposed. A 7-phase BLDC motor is designed and the electrical characteristics are analyzed using FEA program and the power electronics drives for the 7-phase BLDC motor are theoretically analyzed and the actual implementation has been accomplished using Matlab Simulink. PI controller is used for verifying the validity of the proposed model and the informative results are described in detail.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.1
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• pp.38-46
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• 2000

In this paper, robust depth and course controllers of AUV(autonomous underwater vehicles) using LMI-based H$_{\infty}$ servo control are proposed. The $H_{\infty}$ servo problem is modified to an $H_{\infty}$ control problem for the generalized plant that includes a reference input mode, and then a sub-optimal solution that satisfies a given performance criteria is calculated by LMI(Linear Matrix Inequality) approach. The robust depth and course controllers are designed to be satisfied the robust stability about the modeling error generated from the perturbation of the hydrodynamic coefficients and the robust tracking property under sea wave and tide disturbances. The performances of the designed controllers are evaluated by computer simulations, and these simulation results show the applicability of the proposed robust depth and course controller.

• Ocean Systems Engineering
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• v.3 no.1
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• pp.71-77
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• 2013

The effective tracking area of ultra short baseline (USBL) systems strongly relates to the safety of autonomous underwater vehicles (AUVs). This problem has not been studied previously. A method for determining the effective tracking area using acoustic theory is proposed. Ray acoustic equations are used to draw rays which ascertain the effective space. The sonar equation is established in order to discover the available range of the USBL system and the background noise level using sonar characteristics. The available range defines a hemisphere like enclosure. The overlap of the effective space with the hemisphere is the effective area for USBL systems tracking AUVs. Lake and sea trials show the proposed method's validity.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.3
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• pp.124-131
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• 2011

There are many researches in unmanned vehicles such as UGV(Unmanned Ground Vehicle), AUV(Autonomous Underwater Vehicle). In these researches, differential wheeled mobile robots are mainly used to develop the experimental stage algorithm because of the simplicity of modeling and control. Usually a commercial product used in the study, but in order to operate a commercial product to the restrictions because there would need to use a fixed protocol. Using the microprocessor makes the internal sensors(encoder and INS) and external sensors(ultrasonic sensors, infrared sensors) operate and to determine commands for robot operation. This paper propose a mobile robot design for suitable purpose.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.110-117
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• 2022

This paper describes a localization algorithm utilizing relative observations for multiple autonomous underwater vehicles (Multiple-AUVs). In order to maximize the efficiency of operation and mission accomplishment and to prevent problems such as collision and interference, the locations and directions of Multiple-AUVs must be precisely estimated. To estimate the locations and directions, we designed a localization algorithm utilizing relative observations and verified it with simulations based on sensor data sets acquired through real sea experiments. Also, an optimal combination of relative observation information for efficient localization is figured out through combining various relative observations. The proposed method shows improved localization results compared to those only using the navigation algorithm. The performance of localization is improved up to 58% depending on the combination of relative observations.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.173-178
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• 2015

In these days, the world has been increasing the development of various underwater vehicles such as ROVs (Remotely operated underwater vehicles) and AUVs (Autonomous underwater vehicles). And the importance of submarine's maneuverability is especially being emphasized. Therefore, accurate values of the derivatives in equations of motion are required to control motion of the submarines. The aims of the present study are to experimentally derive Hydrodynamic derivatives derived by the vertical planar motion mechanism (VPMM) model test, and to estimate vertical dynamic stability was estimated by using the linear hydrodynamic derivatives, the hydrodynamic derivatives of the submarine, which have a high propriety, were provided by using the fourier analysis of measured forces and moments. Furthermore it is confirmed that the experimental derivatives shows well agreement with the theoretical estimations, and the dynamic stability of the submarine was estimated as a good state, which implies that the value is greater than zero.

• Journal of Ocean Engineering and Technology
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• v.25 no.1
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• pp.27-31
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• 2011

The previously developed method of estimating the propulsion performance of a UUV was applied to the high speed UUV, which is propelled by commercial thrusters. The thrusters were selected with an overdesign mentality; in other words, their capacities were excessive. At that point, the designer's concern was focused on a question regarding at what rpm the UUV could reach the design speed. Because the developed method required thrust coefficient curve data, the researchers asked for the POW data of the thrusters from the manufacturer. From the data, the researchers extracted the thrust coefficient and estimated the rpm value of design speed for the UUV. Finally, the researchers compared the estimated value and the result from a self-propulsion test using a VPMM (Vertical planar motion mechanism) test at a towing tank in MOERI.

• The Journal of Korea Robotics Society
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• v.16 no.4
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• pp.306-312
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• 2021

This paper describes localization of autonomous underwater vehicles(AUV), which can be used when some navigation sensor data are an outlier. In that situation, localization through existing navigation algorithms causes problems in long-range localization. Even if an outlier sensor data occurs once, problems of localization will continue. Also, if outlier sensor data is related to azimuth (direction of AUV), it causes bigger problems. Therefore, a parallel localization module, in which different algorithms are performed in a normal and abnormal situation should be designed. Before designing a parallel localization module, it is necessary to study an effective method in the abnormal situation. So, we propose a localization method through machine learning. For this method, a learning model consists of only Fully-Connected and trains through randomly contaminated real sea data. The ground truth of training is displacement between subsequent GPS data. As a result, average error in localization through the learning model is 0.4 times smaller than the average error in localization through the existing navigation algorithm. Through this result, we conclude that it is suitable for a component of the parallel localization module.

• Geophysics and Geophysical Exploration
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• v.14 no.1
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• pp.80-87
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• 2011

Autonomous underwater vehicles (AUVs) present the important advantage of being able to approach the seafloor more closely than surface vessel surveys can. To collect bathymetric data, bottom material information, and sub-surface images, multibeam echosounder, sidescan sonar (SSS) and subbottom profiler (SBP) equipment mounted on an AUV are powerful tools. The 3000m class AUV URASHIMA was developed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). After finishing the engineering development and examination phase of a fuel-cell system used for the vehicle's power supply system, a renovated lithium-ion battery power system was installed in URASHIMA. The AUV was redeployed from its prior engineering tasks to scientific use. Various scientific instruments were loaded on the vehicle, and experimental dives for science-oriented missions conducted from 2006. During the experimental cruise of 2007, high-resolution acoustic images were obtained by SSS and SBP on the URASHIMA around the northern Kumano Basin off Japan's Kii Peninsula. The map of backscatter intensity data revealed many debris objects, and SBP images revealed the subsurface structure around the north-eastern end of our study area. These features suggest a structure related to the formation of the latest submarine fan. However, a strong reflection layer exists below ~20 ms below the seafloor in the south-western area, which we interpret as a denudation feature, now covered with younger surface sediments. We continue to improve the vehicle's performance, and expect that many fruitful results will be obtained using URASHIMA.