자율무인잠수정의 수중 도킹을 위한 비쥬얼 서보 제어 알고리즘

이판묵(PAN-MOOK LEE),전봉환(BONG-HWAN JEON),이종무(CHONG-MOO LEE) 한국해양공학회 2003 韓國海洋工學會誌 Vol.17 No.1

Autonomous underwater vehicles (AUVs) are unmanned, underwater vessels that are used to investigate sea environments in the study of oceanography. Docking systems are required to increase the capability of the AUVs, to recharge the batteries, and to transmit data in real time for specific underwater works, such as repeated jobs at sea bed. This paper presents a visual servo control system used to dock an AUV into an underwater station. A camera mounted at the nose center of the AUV is used to guide the AUV into dock. To create the visual servo control system, this paper derives an optical flow model of a camera, where the projected motions of the image plane are described with the rotational and translational velocities of the AUV. This paper combines the optical flow equation of the camera with the AUVs equation of motion, and derives a state equation for the visual servo AUV. Further, this paper proposes a discrete-time MIMO controller, minimizing a cost function. The control inputs of the AUV are automatically generated with the projected target position on the CCD plane of the camera and with the AUVs motion. To demonstrate the effectiveness of the modeling and the control law of the visual servo AUV, simulations on docking the AUV to a target station are performed with the 6-dof nonlinear equations of REMUS AUV and a CCD camera.

추력편향방식 AUV의 직진안정성 개선을 위한 고정핀 설계

김동진,권창섭,김연규,박진영,전봉환 제어·로봇·시스템학회 2022 제어·로봇·시스템학회 논문지 Vol.28 No.12

AUVs (Autonomous Underwater Vehicles) have been widely used for various underwater survey missions. In general, cruising type AUVs have torpedo-shaped hull forms for minimizing the hull resistances. It is necessary to ensure there are sufficient straight-line stabilities for a cruising type AUV in order to maintain its desired courses and depths with minimum controls during operations. In this study, vertical and horizontal plane straight-line stabilities of a designed AUV are analyzed based on the captive model tests. VPMM (Vertical Planar Motion Mechanism) tests are carried out to obtain hydrodynamic coefficients of the designed AUV. The AUV shows both vertical and horizontal plane instabilities, its stability margin indices are unsatisfying when compared with the recommended values. But the recommended vertical plane stability margins are subject to very high-speed conditions, so the characteristic equations of the AUV are reconsidered to investigate low-speed vertical plane stabilities in more detail. Next, a pair of horizontal and vertical fins are respectively designed to improve the vertical and horizontal plane stabilities of the AUV. The AUV with fixed fins shows improved stability margin indices within the recommended levels. In addition, the shape of the horizontal fins is properly modified for safe operations. The AUV with the designed vertical fins shows good horizontal plane stability in straight run simulations with step disturbances. And the effects of the horizontal fins are investigated through depth control simulations with biased random disturbances. .

신경회로망 기반의 적응제어기를 이용한 AUV의 운동 제어

이계홍(JI-HONG LI),이판묵(PAN-MOOK LEE),이상정(SANG-JEONG LEE) 한국해양공학회 2002 韓國海洋工學會誌 Vol.16 No.1

This paper presents a neural net based nonlinear adaptive controller for an autonomous underwater vehicle (AUV). AUV's dynamics are highly nonlinear and their hydrodynamic coefficients vary with different operational conditions, so it is necessary for the high performance control system of an AUV to have the capacities of learning and adapting to the change of the AUV's dynamics. In this paper a linearly parameterized neural network is used to approximate the uncertainties of the AUV's dynamics, and the basis function vector of network is constructed according to the AUV's physical properties. A sliding mode control scheme is introduced to attenuate the effects of the neural network's reconstruction errors and the disturbances in AUV's dynamics. Using Lyapunov theory, the stability of the presented control system is guaranteed as well as the uniformly boundedness of tracking errors and neural network's weights estimation errors. Finally, numerical simulations for motion control of an AUV are performed to illustrate the effectiveness of the proposed techniques.

Bearing Only Localization for Multiple AUV with Acoustic Broadcast Communication

Kenichi Fujita,Takumi Matsuda,Toshihiro Maki 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10

This paper presents the method and characteristic of bearing only localization applying for multiple low-cost autonomous underwater vehicles (AUVs). In the proposed method, each AUV equips sensors which are not always accurate enough to estimate position. The method estimates the positions of the AUVs combining the information of the directions from the AUVs to the acoustic source and sensor values on the AUVs. This paper analyzed the capability of this method using the mathematical model of the system with observability rank condition. The result indicates the system has observability as far as the AUV does not move directly from or to the acoustic source. The position of the AUVs was also estimated using the particle filter. The method succeeded in the particles from diverging. We also observed that the accuracy of the estimation depends on the relative position of the acoustic source from the AUV.

상대 관측 정보 신뢰도 판단을 통한 다중자율무인잠수정의 정밀한 위치 추정

이권수,최기환,이필엽,김호성,이한솔,강형주,이지홍 제어·로봇·시스템학회 2022 제어·로봇·시스템학회 논문지 Vol.28 No.6

This paper describes a reliability assessment of relative observations for multiple autonomous underwater vehicles (multiple-AUVs). Swarm control and collision avoidance, the primary issues of a multiple-AUV system, intrinsically need precise localization of Multiple-AUVs, and relative observations of each autonomous underwater vehicle (AUV) are critical to improving localization precision. However, because relative observations are usually measured by ultrasonic sensors, the reliability of sensor data varies depending on the characteristics of each AUVs’ trajectories, as implied in previous our study. Therefore, this paper proposed a reliability assessment method based on the trajectories of each AUV and integrated the derived reliability of relative observations into the multiple-AUV localization algorithm. Consequently, localization performance with real sea experimental data is improved up to 77.4% compared with the previous independent navigation algorithm of each AUV and 60.6% compared with the previous study without the reliability assessment. We conclude that the proposed method is suitable for precise localization through relative observations. .

Design and estimation of a sensing attitude algorithm for AUV self-rescue system

Yang, Yi-Ting,Shen, Sheng-Chih Techno-Press 2017 Ocean systems engineering Vol.7 No.2

This research is based on the concept of safety airbag to design a self-rescue system for the autonomous underwater vehicle (AUV) using micro inertial sensing module. To reduce the possibility of losing the underwater vehicle and the difficulty of searching and rescuing, when the AUV self-rescue system (ASRS) detects that the AUV is crashing or encountering a serious collision, it can pump carbon dioxide into the airbag immediately to make the vehicle surface. ASRS consists of 10-DOF sensing module, sensing attitude algorithm and air-pumping mechanism. The attitude sensing modules are a nine-axis micro-inertial sensor and a barometer. The sensing attitude algorithm is designed to estimate failure attitude of AUV properly using sensor calibration and extended Kalman filter (SCEKF), feature extraction and backpropagation network (BPN) classify. SCEKF is proposed to be used subsequently to calibrate and fuse the data from the micro-inertial sensors. Feature extraction and BPN training algorithms for classification are used to determine the activity malfunction of AUV. When the accident of AUV occurred, the ASRS will immediately be initiated; the airbag is soon filled, and the AUV will surface due to the buoyancy. In the future, ASRS will be developed successfully to solve the problems such as the high losing rate and the high difficulty of the rescuing mission of AUV.

An In-situ Correction Method of Position Error for an Autonomous Underwater Vehicle Surveying the Sea Floor

Lee, Pan-Mook,Jun, Bong-Huan,Park, Jin-Yeong,Shim, Hyung-Won,Kim, Jae-Soo,Jung, Hun-Sang,Yoon, Ji-Young Korean Society of Ocean Engineers 2011 International journal of ocean system engineering Vol.1 No.2

This paper presents an in-situ correction method to compensate for the position error of an autonomous underwater vehicle (AUV) near the sea floor. AUVs generally have an inertial navigation system assisted with auxiliary navigational sensors. Since the inertial navigation system shows drift in position without the bottom reflection of a Doppler velocity log, external acoustic positioning systems, such as an ultra short baseline (USBL), are needed to set the position without surfacing the AUV. The main concept of the correction method is as follows: when the AUV arrives near the sea floor, the vehicle moves around horizontally in a circular mode, while the USBL transceiver installed on a surface vessel measures the AUV's position. After acquiring one data set, a least-square curve fitting method is adopted to find the center of the AUV's circular motion, which is transferred to the AUV via an acoustic telemetry modem (ATM). The proposed method is robust for the outlier of USBL, and it is independent of the time delay for the data transfer of the USBL position with the ATM. The proposed method also reduces the intrinsic position error of the USBL, and is applicable to the in-situ calibration as well as the initialization of the AUVs' position. Monte Carlo simulation was conducted to verify the effectiveness of the method.

최소자승법과 Kalman Filter 를 이용한 AUV 의 DGPS 기반 Localization 의 위치 오차 감소

엄현섭(Hyeon Seob Eom),김지언(Ji Yen Kim),백준영(Jun Young Baek),이민철(Min Cheol Lee) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.10

It is generally important to get a precise position information for autonomous unmanned vehicle(AUV) to run safely. For getting the position of AUV, the GPS has been using to navigation in a vehicle. Though it is useful to finding a position, it is difficult to precisely control a trajectory of the AUV due to large measuring error which may reach over 10 meters. Therefore to apply AUV it needs to compensate for the error. This paper proposes a method to more precisely localize AUV using three low-cost differential global positioning systems (DGPS). The distance errors between each DGPS are minimized as using the least square method (LSM) and the Kalman filter to eliminate a Gaussian white noise. The selected DGPS is cheaper and easier to set up than the RTK-GPS. It is also more precise than the general GPS. The proposed method can compensate the relatively position error according to stationary and moving distance of the AUV. For evaluating the algorithm by simulation, the DGPS signal with the Gaussian white noise to any points is generated by the AR model and compared with the measurement signal. It is confirmed that the proposed method can effectively compensate the position error as comparing with the measurement signal. The compensated position signal can be used to localize and control the AUV in the road.

FRP에 의한 무인잠수정의 설계와 구조해석

김윤해(Yun-Hae Kim),배성열(Sung-Youl Bae),조영대(Young-Dae Jo),문경만(Kyung-Man Moon) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.11

This research investigated to find out the possibilities of applying FRPs to the AUVs. In this study, two kinds of metal materials, which is one of the popularly used materials for manufacturing AUVs, and 6 kinds of FRP materials were considered. Material properties of FRPs were derived by tensile tests and chemical analysis. Moreover, various types of AUVs were designed by 8 kinds of materials. From structural analysis, we can find out that the weights of AUV by CFRP-Autoclave could be reduced by 60% in comparison with the weights of AUV by Al 7075-T6. Also, 40% weight reduction could be expected compared to the AUV by Ti-6Al-4V. In this result, we could conclude that the material of CFRP-Autoclave have various merits and potentialities as one of the AUV materials.

자율무인잠수정의 위치 기반 운항 중 정렬 기법

추진우,이권수,이필엽,김호성,이한솔,박대길,이지홍 제어·로봇·시스템학회 2020 제어·로봇·시스템학회 논문지 Vol.26 No.8

This paper describes a position based in-motion alignment method for underwater navigation of an AUV(Autonomous Underwater Vehicle). For proper estimation of the position and orientation of the AUV the navigation algorithm requires accurate initial values of its position and attitude. However, it is difficult to obtain exact attitude of the AUV in the marine environment, because of the AUV’s body drift caused by flow of the water. To avoid this, in general, the initial alignment is performed on shore using gravitational acceleration, with further launching of AUV into the water. In this paper, we propose the in-motion alignment algorithm that is able to accurately estimate azimuth in the marine environment. Additionally, the proposed method allows to correct velocity of the AUV. .