• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.41-46
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• 2004

In this paper, we study the stabilization control if an underwater vehicle from its initial posture to its desired one. We assume tint the underwater vehicle has velocity constraint, i.e. it has no velocity component for some direction. Our approach is based on the nonholonomic system which am derived from velocity constraints that cannot integrable. We proposed a control strategy for posture control of the underwater vehicle using multi-rate digital control. The proposed control scheme is applied to the berthing control if an underwater vehicle and verified the effectiveness if control strategy by numerical simulation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.135-140
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• 2004

In this paper, we study the posture control of an underwater vehicle with nonholonomic constraint. Generally, systems with nonholnomic constraints cannot be stabilized to an equilibrium points by smooth state feedback control. Therefore, we proposed a control strategy for posture control of the underwater vehicle using backstepping control. The proposed control scheme is applied to the posture control of an underwater vehicle and verified the effectiveness of control strategy by numerical simulation.

• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.443-450
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• 2018

A receiving array system can be applied for tonal noise analysis of underwater vehicles, but it is difficult to install and operate, and a lot of cost is required. In order to overcome this problem, this paper proposes a method to measure the tonal noise of underwater vehicle after synthesizing a virtual array using single receiver. The proposed method compensates the Doppler frequency and time delay caused by the movement of the underwater sound source and applies the focused beamforming technique. The performance of the proposed method was analyzed via simulation.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.469-474
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• 2004

In this paper, we study the posture control of an underwater vehicle with nonholonomic constraint. Generally, systems with nonholnomic constraints cannot be stabilized to an equilibrium points by smooth state feedback control. For the nonholonomic underwater vehicle system, we applied coordinate transformation to get multi-chained system We proposed non smooth feedback controller using backstepping method for stabilizing the multi chained form system Applying inverse input transformation to the non smooth feedback controller, we can get posture controller of the underwater vehicle with nonholonomic constraint. The proposed control scheme is applied to the posture control qf an underwater vehicle and verified the effectiveness of control strategy by numerical simulation.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.240-243
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• 2009

본 논문에서는 수중에서 이동하는 무인잠수정 및 수중이동체의 위치를 측정하는 방법 중의 하나인 동적 단기선 방식(SBL)에 의한 무인잠수정의 위치측정에 대한 방법을 하이드로폰과 DAQ(Data Aquisition) 시스템을 이용하여 수조에서 테스트를 수행하였고, 실 해역에서의 실험을 실시하였다. 실험을 위해서 4개의 센서가 수조의 벽면에 고정이 되어 있으며, 이동체와 고정된 4개의 센서가 신호를 송수신함으로써 상호간의 위치추적이 가능하게 하는 시뮬레이션을 실시하였으며, 제안하는 SBL시스템과 장기선 방식(Long baseline)을 비교하기위한 시뮬레이션을 실시하여 두 시스템을 비교하였다. 측정된 신호는 DAQ 시스템을 이용하여 데이터를 취득하였고, Labview 프로그램을 이용하여 실시간으로 무인잠수정의 위치를 추정하였다. 위치추정에 사용된 알고리즘은 삼각측량법에 의한 방법을 사용하였으며, X, Y방향에 대해서는 비교적 오차가 적은 추정 결과를 나타내었으나 Z방향에 대하여서는 큰 오차를 보여 데이터로 사용할 수 가 없었다. 이는 수중이동체의 수심측정 센서를 이용하여 보완할 수 있을 것으로 본다. 향후 연구로는 위치추정 알고리즘을 보완하여 실제 선박 선저부에 센서가 부착되었을 경우에 대한 적용연구를 진행할 예정이며, 위치추정 알고리즘을 발전시켜 3차원에서의 정확한 위치 추적을 가능하게 할 예정이다.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.6
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• pp.1083-1088
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• 2019

Even though the transmission performance is very important factor for not only study and development but also for design, implementation, and operation of underwater MANET. There is a trend of using it as a measurement factor for comparing and analyzing degree of network performance. In this paper, movement pattern using transmission performance is analyzed to enlarge the use of transmission performance in underwater MANET. The relation between transmission performance and movement pattern is firstly considered and then through this consideration, causing effects of movement pattern to transmission performance is studied. Results of this study can be used as an important base to predict and analyze movement pattern through measuring of transmission performance of moving objects in underwater environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.235-242
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• 2006

This paper proposes the new efficient system design strategies for the acoustic-based underwater communication system and it's media access protocol, which make it possible to control the multiple vehicles for underwater duty working by the surface plant. For an approach to implementation of the system, it is inevitable to establish acoustic-based underwater digital communication network to exchange the information between a surface plant and multiple vehicles in underwater.

• The Journal of the Acoustical Society of Korea
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• v.39 no.2
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• pp.69-76
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• 2020

This paper deals with a method of transmitting depth information of a high-speed underwater vehicle. The depth information signal transmitted from the high-speed mobile object is received with high frequency variability. In the proposed method, we apply not only frequency synchronization but also additional synchronization on the time axis like the existing method. In the case of a Doppler frequency bank with less resolution than the conventional method through simulations performed in the environment moving up to 50 kn, and the depth information is recovered using the proposed method, the error rate of 6 % ~ 9 % is reduced to 0.2 % ~ 1 %.

• The Journal of the Acoustical Society of Korea
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• v.26 no.1
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• pp.48-54
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• 2007

In this paper we have implemented a 3-D PL (Position Location) system to estimate the 3-dimensional position of a moving object in underwater environments. In this research, we let four sensors fixed in different Positions and moving sensorsto communicate with each other to find the 3-dementianal positions for both the fixed and moving objects. Using this we were also able to control the moving object remotely. When finding the position, we calculated the norm of the Jacobian matrix every iteration in the Newton algorithm. Also by using a different initial value for calculating the solution when the norm became higher than the critical value and the solution from the inverse matrix became unstable, we could find a more reliable position for the moving object. The proposed algorithm was used in implementing a DSP system capable of real-time position location. To verify the performance, experiments were done in a water tank. As a result we could see that our system could located the position of an object every 2 seconds with a error range of 5cm.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.42-48
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• 2006

This paper proposes the new efficient system design strategies for the acoustic-based underwater multiple modem and media access control protocol. The system aims to establish the acoustic-based communication network of an underwater vehicles for deep sea mining, which ensures a certain level of maximum throughput regardless of the propagation delay of acoustic and allows fast data transmission through the acoustic-based multiple channel.