• Title/Summary/Keyword: DVL

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Implementation and Performance Comparison for an Underwater Robot Localization Methods Using Seabed Terrain Information (해저 지형정보를 이용하는 수중 로봇 위치추정 방법의 구현 및 성능 비교)

  • Noh, Sung Woo;Ko, Nak Yong;Choi, Hyun Taek
    • Journal of the Korean Institute of Intelligent Systems
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    • v.25 no.1
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    • pp.70-77
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    • 2015
  • This paper proposes an application of unscented Kalman filter(UKF) for localization of an underwater robot. The method compares the bathymetric measurement from the robot with the seabed terrain information. For the measurement of bathymetric range to seabed, it uses a DVL which typically yields four range data together with velocity of the robot. Usual extended Kalman filter is not appropriated for application in case of terrain navigation, since it is not feasible to derive Jacobian for the bathymetric range measurement. Though particle filter(PF) is a nice solution which doesn't require Jacobian and can deal with non-linear and non-Gaussian system and measurement, it suffers from heavy computational burden. The paper compares the localization performance and the computation time of the UKF approach and PF approach. Though there have been some UKF methods which are used for underwater navigation, application of the UKF for bathymetric localization is rare. Especially, the proposed method uses only four range data whereas many of the bathymetric navigation methods have used multibeam sonar which yields hundreds of scanned range data. The result shows feasibility of the UKF approach for terrain-based navigation using small numbers of range data.

Implementation and field test for autonomous navigation of manta UUV (만타형 무인 잠수정의 개발과 실해역 성능시험)

  • Ko, Sung-Hyub;Kim, Dong-Hee;Kim, Joon-Young
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.6
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    • pp.644-652
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    • 2013
  • This paper describes the development and field experiments of Manta-type Unmanned Underwater Vehicle (UUV). Various simulations for Manta UUV are performed by using the nonlinear 6-DOF motion of equations. Through this simulation we verified the motion performances of Manta UUV. To acquire the blueprint of Manta UUV, it was designed with the simulation results. The Manta UUV uses a Doppler Velocity Log (DVL), gyrocompass, GPS, pressure sensor and other minor sensors, applied to measure the motion, position and path of Manta UUV. For its propulsion and changing a direction in the underwater, one vertical fin and four horizontal fins are installed at the hull of UUV. The Manta UUV system was verified with motion and autonomous navigation test at field.

Effect of Histone Deacetylase Inhibitors on Differentiation of Human Bone Marrow-derived Stem Cells Into Neuron-like Cells

  • Jang, Sujeong;Park, Seokho;Cho, Hyong-Ho;Yang, Ung;Kang, Maru;Park, Jong-Seong;Park, Sah-Hoon;Jeong, Han-Seong
    • Journal of Integrative Natural Science
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    • v.12 no.4
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    • pp.133-141
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    • 2019
  • Mesenchymal stem cells (MSCs) are known to differentiate into multiple lineages, making neurogenic differentiation an important target in the clinical field. In the present study, we induced the neurogenic differentiation of cells using histone deacetylase (HDAC) inhibitors and studied their mechanisms for further differentiation in vitro. We treated cells with the HDAC inhibitors, MS-275 and NaB; and found that the cells had neuron-like features such as distinct bipolar or multipolar morphologies with branched processes. The mRNA expressions encoding for NEFL, MAP2, TUJ1, OLIG2, and SYT was significantly increased following HDAC inhibitors treatment compared to without HDAC inhibitors; high protein levels of MAP2 and Tuj1 were detected by immunofluorescence staining. We examined the mechanisms of differentiation and found that the Wnt signaling pathway and downstream mitogen-activate protein kinase were involved in neurogenic differentiation of MSCs. Importantly, Wnt4, Wnt5a/b, and Wnt11 protein levels were highly increased after treatment with NaB; signals were activated through the regulation of Dvl2 and Dvl3. Interestingly, NaB treatment increased the levels of JNK and upregulated JNK phosphorylation. After MS-275 treatment, Wnt protein levels were decreased and GSK-3β was phosphorylated. In this cell, HDAC inhibitors controlled the non-canonical Wnt expression by activating JNK phosphorylation and the canonical Wnt signaling by targeting GSK-3β.

Improvement of Position Estimation Based on the Multisensor Fusion in Underwater Unmanned Vehicles (다중센서 융합 기반 무인잠수정 위치추정 개선)

  • Lee, Kyung-Soo;Yoon, Hee-Byung
    • Journal of the Korean Institute of Intelligent Systems
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    • v.21 no.2
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    • pp.178-185
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    • 2011
  • In this paper, we propose the position estimation algorithm based on the multisensor fusion using equalization of state variables and feedback structure. First, the state variables measured from INS of main sensor with large error and DVL of assistance sensor with small error are measured before prediction phase. Next, the equalized state variables are entered to each filter and fused the enhanced state variables for prediction and update phases. Finally, the fused state variables are returned to the main sensor for improving the position estimation of UUV. For evaluation, we create the moving course of UUV by simulation and confirm the performance of position estimation by applying the proposed algorithm. The evaluation results show that the proposed algorithm is the best for position estimation and also possible for robust position estimation at the change period of moving courses.

Velocity Aided Navigation Algorithm to Estimate Current Velocity Error (해조류 속도 오차 추정을 통한 속도보정항법 알고리즘)

  • Choi, Yun-Hyuk
    • Journal of Advanced Navigation Technology
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    • v.23 no.3
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    • pp.245-250
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    • 2019
  • Inertial navigation system has navigation errors because of the error of inertial measurement unit (IMU) and misalignment over time. In order to solve this problem, aided navigation system is performed using global navigation satellite system (GNSS), speedometer, etc. The inertial navigation system equipped with underwater vehicle mainly uses speedometer and performed aided navigation because satellite signals do not pass through underwater. There are DVL, EM-Log, and RPM in the speedometer, and the sensors are applied according to the system environment. This paper describes velocity aided navigation using RPM of inertial navigation system operating in high speed and deep water environment. In addition, we proposes an algorithm to compensate the limit of RPM with straight direction and the current velocity error. There are results of monte-calo simulation to prove performance of the proposed algorithm.

Design and Analysis of ATM-based Video Stream Switch for Supporting Digital Video Library Service (디지털 비디오 라이브러리 서비스를 지원하는 ATM-기반 비디오 스트림 스위치의 설계 및 분석)

  • Park, Byeong-Seop;Kim, Seong-Su
    • The KIPS Transactions:PartC
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    • v.8C no.2
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    • pp.164-172
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    • 2001
  • 최근 인터넷의 확산과 더불어 디지털 비디오 라이브러리(DVL : Digital Video Library) 서비스에 대한 관심이 고조되고 있다. 그러나 현재의 통신망 대역폭과 스위칭 환경 하에서는 종단간 QoS 보장하는데 많은 제약사항이 존재한다. 따라서 본 논문에서는 비디오 스트림 처리를 효율적으로 수행하여, 지연-처리율 특성을 만족할 수 있는 스트림 스위칭 구조를 제안하고 이에 대한 성능을 분석하였다. 제안된 ATM-기반 스트림 스위치는 각각 다중화되는 CBR(Constant Bit Rate) 및 VBR(Variable Bit Rate) 스트림의 QoS(Quality of Service)를 보장해야만 한다. 성능분석 결과는 제안된 스위치의 처리율이 r=4일 때 약 0.996의 값을 보였으며, 지연시간도 부하가 0.7 이하일 때 2미만으로 특정되었다. 이 결과는 제안된 구조가 적당한 입력 스트림의 그룹핑을 통하여 비디오 응용을 위한 처리율 및 지연 요구사항 QoS를 보장할 수 있음을 보여준다.

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A Basic Study of Water Basin Experiment for Underwater Robot with Improving usability (사용자 운용 편의성을 위한 수중로봇 MR-1의 수조실험에 관한 연구)

  • Nam, Keonseok;Ryu, Jedoo;Ha, Kyoungnam
    • The Journal of Korea Robotics Society
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    • v.15 no.1
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    • pp.32-38
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    • 2020
  • This paper describes a method for tracking attitude and position of underwater robots. Underwater work with underwater robots is subject to differences in work efficiency depending on the skill of the operator and the utilization of additional sensors. Therefore, this study developed an underwater robot that can operate autonomously and maintain a certain attitude when working underwater to reduce difference of work efficiency. The developed underwater robot uses 8 thrusters to control 6 degrees of freedom motion, IMU (Inertial Measurement Unit), DVL (Doppler Velocity Log) and PS (Pressure Sensor) to measure attitude and position. In addition, the thruster allocation algorithm was designed to follow the control desired value using 8 thrusters, and the motion control experiments were performed in the engineering water basin using the thruster allocation method.

Sensor Fusion for Underwater Navigation of Unmanned Underwater Vehicle (무인잠수체의 수중항법을 위한 센서퓨전)

  • 주민근;서주노;송광섭;이판묵;홍석원;박영일
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.175-175
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    • 2000
  • In this Paper we propose a navigation algorithm which can be used to estimate state vectors such as position and velocity for its motion control using multi-sensor output measurements. The output measurement we will use in estimating the state is a series of known multi-sensor asynchronous outputs with measurement noise. This paper investigates the Extended Kalman Filtering method to merge asynchronous heading, heading rate, velocity of DVL, and SSBL information to produce a single state vector. Different complexity of Kalman Filter, with biases and measurement noise, are investigated with theoretically data from KRISO's AUV. All levels of complexity of the Kalman Filters are shown to be much more close and smooth to real trajectories then the basic underwater acoustic navigation system comment)'used aboard underwater vehicle.

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Measurement of Moving Object Velocity and Angle in a Quasi-Static Underwater Environment Through Simulation Data and Spherical Convolution (시뮬레이션 데이터와 Spherical Convolution을 통한 준 정적인 수중환경에서의 이동체 속도 및 각도 측정)

  • Baegeun Yoon;Jinhyun Kim
    • The Journal of Korea Robotics Society
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    • v.18 no.1
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    • pp.53-58
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    • 2023
  • In general, in order to operate an autonomous underwater vehicle (AUV) in an underwater environment, a navigation system such as a Doppler Log (DVL) using a Doppler phenomenon of ultrasonic waves is used for speed and direction estimation. However, most of the ultrasonic sensors in underwater is large for long-distance sensing and the cost is very high. In this study, not only canal neuromast on the fish's lateral lines but also superficial neuromast are studied on the simulation to obtain pressure values for each pressure sensor, and the obtained pressure data is supervised using spherical CNN. To this end, through supervised learning using pressure data obtained from a pressure sensor attached to an underwater vehicle, we can estimate the speed and angle of the underwater vehicle in a quasi-static underwater environment and propose a method for a non-ultrasonic based navigation system.

Development of the Localization Algorithm for a Hovering-type Autonomous Underwater Vehicle using Extended Kalman Filter (확장칼만필터를 이용한 호버링타입 무인잠수정의 위치추정알고리즘 개발)

  • Kang, Hyeon-seok;Hong, Sung-min;Sur, Joo-no;Kim, Dong-hee;Jeong, Jae-hun;Jeong, Seong-hoon;Choi, Hyeung-sik;Kim, Joon-young
    • Journal of Advanced Navigation Technology
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    • v.21 no.2
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    • pp.171-178
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    • 2017
  • In this paper, in order to verify the performance of a localization algorithm using GPS as an auxiliary sensor, the algorithm was applied to a hovering-type autonomous underwater vehicle (AUV) to perform a field test. The applied algorithm is an algorithm to improve the accumulated positional error of dead reckoning using doppler velocity logger(DVL) and tilt-compensated compass module (TCM) mounted on the AUV. GPS when surfaced helps the algorithm to estimate the position and the heading bias error of TCM for geodetic north, which makes it possible to perform dead reckoning on north-east-down (NED) coordinates. As a result of field test performing heading control, it was judged that the algorithm could improve the positional error, enhance the operational capability of AUV and contribute to the research of underwater navigation depending on a magnetic compass.