• 제어로봇시스템학회논문지
• /
• 제3권3호
• /
• pp.227-237
• /
• 1997

Autonomous Underwater Vehicles(AUVs) have become an important tool for various purposes in subsea: inspection, recovery, construction, etc., and the development of autonomous control system is luglay desirable- thete zffe many problems associated with designing the control system for AUV due to unknown underwater envimn-Tnent, the possibility of subsystem failures, and unpredictable changes in the dynamics of the vehicle. In this paper, an autonomous control system based on the intelligent control theory to enhance operation efficiency of the ALTV is presented. The control system has a hierarchical structure which consists of mission planning level, mission control level, navigation level, and execution level. The performance of the control system is investigated by computer simulation. The results show that the proposed control system can be applied successfully to the AUV in spite of the possibility of failures in the vehicle and the collision hazard in the sea environment.

• IEIE Transactions on Smart Processing and Computing
• /
• 제4권4호
• /
• pp.216-223
• /
• 2015

The autonomous underwater vehicle (AUV) is being widely researched in order to achieve superior performance when working in hazardous environments. This research focuses on using image processing techniques to estimate the AUV's egomotion and the changes in orientation, based on image frames from different time frames captured from a single high-definition web camera attached to the bottom of the AUV. A visual odometry application is integrated with other sensors. An internal measurement unit (IMU) sensor is used to determine a correct set of answers corresponding to a homography motion equation. A pressure sensor is used to resolve image scale ambiguity. Uncertainty estimation is computed to correct drift that occurs in the system by using a Jacobian method, singular value decomposition, and backward and forward error propagation.

• 한국해양공학회지
• /
• 제8권2호
• /
• pp.131-140
• /
• 1994

Dynamics of AUV has heavy nonlinearities and many unknown parameters due to its bluff shape and low cruising speed. Intelligent algorithms, therefore, are required to overcome these nonlinearities and unknown system dynamics. Several identification techniques have been suggested for the application of control of underwater vehicles during last decade. This paper applies the neural network to identification and motion control problem of AUVs. Nonlinear dynamic systems of an AUV are identified using feedforward neural network. Simulation results show that the learned neural network can generate the motion of AUV. This paper, also, suggest an adaptive control scheme up-dates the controller weights with reference model and feedforward neural network using error back propagation.

• 한국재난정보학회:학술대회논문집
• /
• 한국재난정보학회 2017년 정기학술대회
• /
• pp.271-272
• /
• 2017

자외선 에너지는 미생물의 DNA를 파괴함으로써 살균 효과를 일으킨다. 자외선 방사로 공기 중 미생물에 대하여 높은 살균력을 얻기 위해선 강한 자외선 강도와, 흐르는 공기가 충분한 시간 동안 강한 자외선에 노출되어야 하므로 균일한 자외선 방사는 매우 중요하다. 기존 UV살균 시스템은 강한 자외선 에너지와 공기의 빠른 이동에 필요한 UV방사의 균일성을 제공하지 않았다. 하지만 HDS의 BioProtector 제품에 사용된 Advanced UV System(AUVS) 반사 캐비티 기술은 매우 높은 수준의 균일성을 생성함으로써 이 문제에 대한 해결책을 제공하며, 미생물 살균에 가장 효과적인 UV파장을 사용하여 6 LOG KILL (100만마리의 미생물 투입시 1마리 이하생존) 수준의 살균 효과를 만들었다.

• 한국기계가공학회지
• /
• 제20권4호
• /
• pp.66-72
• /
• 2021

Since the behavior of an autonomous underwater vehicle (AUV) is influenced by disturbances and moments that are not accurately known, the depth control law of AUVs must have the ability to track the input signal and to reject disturbances simultaneously. Here, we proposed robust tracking control for controlling the depth of an AUV. An augmented closed-loop system is represented by an error dynamic equation, and we can easily show the asymptotic stability of the overall system by using a Lyapunov function. The robust tracking controller is consisted of the internal model of the command signal and a state feedback controller, and it has the ability to track the input signal and reject disturbances. The closed-loop control system is robust to parameter uncertainties. Simulation results showed the control performance of the robust tracking controller to be better than that of a P + PD controller.

• 한국해양공학회지
• /
• 제38권3호
• /
• pp.115-123
• /
• 2024

USBL systems are essential for providing accurate positions of autonomous underwater vehicles (AUVs). On the other hand, the accuracy can be degraded by outliers because of the environmental conditions. A failure to address these outliers can significantly impact the reliability of underwater localization and navigation systems. This paper proposes a novel outlier rejection algorithm for AUV localization using Voronoi diagrams and query point calculation. The Voronoi diagram divides data space into Voronoi cells that center on ultra-short baseline (USBL) data, and the calculated query point determines if the corresponding USBL data is an inlier. This study conducted experiments acquiring GPS and USBL data simultaneously and optimized the algorithm empirically based on the acquired data. In addition, the proposed method was applied to a sensor fusion algorithm to verify its effectiveness, resulting in improved pose estimations. The proposed method can be applied to various sensor fusion algorithms as a preprocess and could be used for outlier rejection for other 2D-based location sensors.

• Ocean Systems Engineering
• /
• 제4권1호
• /
• pp.1-19
• /
• 2014

Hydrodynamic coefficients strongly affect the dynamic performance of autonomous underwater vehicles (AUVs). A novel kind of underwater vehicle (Heavier-than-water AUV) with higher density than water is presented, which is different from conventional ones. RANS method and overlapping grids are used to simulate the flow field around the vehicle. Lifts, drags and moments of different attack and drift angles in steady state are calculated. The hydrodynamic performances and how the forces change with the attitude are analyzed according to the flow field structure. The steady-state results using overlapping grid method are compared with those of software FLUENT and wind tunnel tests. The calculation results show that the overlapping grid method can well simulate the viscous flow field around the underwater vehicle. Overlapping grid skills have also been used to figure out the planar-motion-mechanism (PMM) problem of Heavier-than-water AUV and forecast its hydrodynamic performance, verifying its effectiveness in dealing with the dynamic problems, which would be quite helpful for design and control of Heavier-than-water AUV and other underwater vehicles.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
• /
• pp.327-330
• /
• 2006

With the increasing requirements for the survey and development of the ocean, the demands on the of AUV(Autonomous Underwater Vehicle) technologies have been increased. Reconstruction and replay of the AUV motion on the basis of the data stored during the execution of mission, can help the development of control strategies for AUVs such as mission planning and control algorithms. While an AUV cruises for her mission, her attitude and position data are is recorded. The data can be used for visualization of the motion in off-line. However, because most of the position data gathered from acoustic sensors have long time-interval and include intermittent faulty signal, the replayed motion by the graphic simulator can not demonstrate the motion as a smooth movie. In this paper, interpolation methods are surveyed to reconstruct the AUV position data. Then, an efficient 3D visualization method for AUV motion using the interpolation method is proposed. Simulation results arc also included to verify the proposed method.

• 한국지능시스템학회논문지
• /
• 제21권1호
• /
• pp.112-119
• /
• 2011

본 연구는 주변 환경정보와 장애물정보, 위치정보를 이용하여 무인잠수정의 운항 환경에 존재하는 다양한 장애물들에 대한 충돌위험도를 산출하는 시스템을 제안한다. 충돌위험도는 퍼지추론을 사용하여 산출하며, TCPA, DCPA, 거리를 인자로 사용하게 된다. 또한 삼차원환경에서 TCPA와 DCPA를 획득하는 방법을 제안한다. 충돌위험도는 충돌회피시스템에 제공되며, 시뮬레이션을 통하여 그 경제성과 안전성에서의 효율성을 보인다.

• 한국해양공학회지
• /
• 제23권4호
• /
• pp.47-51
• /
• 2009

Thrust is one of the important performance characteristics of an AUV. At the design stage, the resistance of an AUV at its maximum speed is estimated and then the thrust system is designed, including the propeller diameter, propeller rpm, driving system, and required power. However, it is not possible to be certain that the thrust system has been correctly designed until the AUV is launched and its speed is measured. If data from a propeller open-water test is available, the thrust and torque of the propeller at a certain speed can be estimated. In addition, if the motor's torque characteristics are available, the maximum speed saturated by the induced propeller torque can be estimated. In this paper, an easy technique for estimating the maximum speed of an AUV will be shown, even in a case where additional resistance is gained from appendages not considered at the design stage. Furthermore, the thrust performance changes by adjusting the diameter of the propeller can be easily investigated.