• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 한국항해항만학회 2010년도 추계학술대회
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• pp.1-3
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• 2010

수중 무인항체(Autonomous Underwater Vehicle, AUV)를 고정밀, 고위험 임무수행 분야에 이용하기 위해서는 연속적이고 정확한 항법정보를 제공하는 기술이 반드시 필요하다. 특히, 최근에는 항공분야에서 국내외적으로 연속적이고 정확한 항법정보를 제공하기 위하여 여러 가지 센서를 결합한 통합 항법시스템에 관한 연구가 활발하며, GPS나 음향장치를 관성센서와 통합하는 방법이 대표적이다. 하지만 수중 무인항체에 경우는 해수면 노출로 인한 탐사시간 장기화와 음향장치 설치 및 회수의 한계로 인하여 GPS나 음향장치 이외에 센서를 이용한 통합 항법시스템의 필요성이 커지고 있다. 본 논문에서는 자율성이 높으면서, 적은 비용으로 설치가 가능한 영상센서를 이용하여 항법성능을 효과적으로 증대시키는 Vision/INS 통합 항법을 제안한다. 제안한 통합 항법알고리즘은 외부표정요소 직접결정기법을 이용하여 영상 데이터로부터 항체의 위치와 자세를 추정하고, 추정된 결과를 INS의 추정치와 비교한다. 그리고 추정한 위치와 자세오차를 입력으로 칼만필터를 구동하도록 설계하였다. 모의실험을 통해 제안한 방법의 유효성을 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• 제47권6호
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• pp.33-42
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• 2010

This research propose a practical guidance system considering ocean currents in real sea operation. Optimality of generated path is not an issue in this paper. Way-points from start point to possible goal positions are selected by experienced human supervisors considering major ocean current axis. This paper also describes the implementation of a precise underwater navigation solution using multi-sensor fusion technique based on USBL, GPS, DVL and AHRS measurements in detail. To implement the precise, accurate and frequent underwater navigation solution, three strategies are chosen. The first one is the heading alignment angle identification to enhance the performance of standalone dead-reckoning algorithm. The second one is that absolute position is fused timely to prevent accumulation of integration error, where the absolute position can be selected between USBL and GPS considering sensor status. The third one is introduction of effective outlier rejection algorithm. The performance of the developed algorithm is verified with experimental data of mine disposal vehicle and deep-sea ROV.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제26권12호
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• pp.1890-1897
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• 2022

In this paper, we design a navigation filter for an underwater glider. Underwater gliders are low-cost, reusable, and can be used for a long time. Two types of filters are designed considering characteristics such as small size, low cost, and low power. The navigation filter estimates the reference velocity of the underwater glider's body frame based on the minimum sensor output. The sensor configuration of the first filter consists of an accelerometer, a magnetometer, and a depth sensor. the second filter include extra a gyroscope in the same configuration. The estimated velocity is fused with the attitude, converted into the velocity of the navigation frame and finally the position is estimated. To analyze the performance of the proposed filter, analysis was performed using Monte Carlo numerical analysis method, and the results were analyzed with standard deviation (1σ). Standard deviations of each filter's position error are 334.34m, 125.91m.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제17권9호
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• pp.2227-2232
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• 2013

To obtain the system requirement specification in the beginning of the precision guidance system development, the effectiveness and reliability analysis for the system are necessary. The main purpose of this research is to obtain the system requirement specification for the high speed unmanned underwater vehicles by carrying out the effectiveness analysis using the modeling and simulation scheme. The effectiveness is position error for target position. Reaching accuracy is expected to be affected by the navigation sensor parameter. Assume that the navigation sensors that is consist of inertial navigation system(INS) and doppler velocity log(DVL) is the parameter. To analyze the effectiveness of each parameter, Monte-Carlo numerical simulation is performed in this research. The effectiveness analysis is carried out using circular error probability(CEP) and variance analyze scheme. Considering the cost function, the specification of the navigation sensor is provided. The cost function is consist of the INS and DVL specification and the price of those sensors.

• Journal of the Institute of Electronics and Information Engineers
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• 제54권3호
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• pp.108-118
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• 2017

This paper presents experimental results of realtime sonar-based SLAM (simultaneous localization and mapping) using probability-based landmark-recognition. The sonar-based SLAM is used for navigation of underwater robot. Inertial sensor as IMU (Inertial Measurement Unit) and DVL (Doppler Velocity Log) and external information from sonar image processing are fused by Extended Kalman Filter (EKF) technique to get the navigation information. The vehicle location is estimated by inertial sensor data, and it is corrected by sonar data which provides relative position between the vehicle and the landmark on the bottom of the basin. For the verification of the proposed method, the experiments were performed in a basin environment using an underwater robot, yShark.

• Journal of Advanced Navigation Technology
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• 제23권3호
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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.

• Journal of Ocean Engineering and Technology
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• 제24권3호
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• pp.46-51
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• 2010

This paper describes the implementation of a precise underwater navigation solution using a multi-sensor fusion technique based on USBL, DVL, and IMU measurements. To implement this precise underwater navigation solution, three strategies are chosen. The first involves heading alignment angle identification to enhance the performance of a standalone dead-reckoning algorithm. In the second, the absolute position is found quickly to prevent the accumulation of integration error. The third one is the introduction of an effective outlier rejection algorithm. The performance of the developed algorithm was verified with experimental data acquired by the deep-sea ROV, Hemire, in the East-sea during a survey of a methane gas seepage area at a 1,500 m depth.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제19권11호
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• pp.2751-2757
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• 2015

To obtain the system requirement specification in the beginning of the precision guidance and control system development, the effectiveness and reliability analysis for the system are necessary. The main purpose of this research is to obtain the system requirement specification by carrying out the effectiveness analysis using the modeling and simulation(M&S) scheme. M&S model is constructed using 6-DOF dynamic model, environment model, guidanc -navigation & control model. Assume that the navigation sensor is consist of inertial navigation sensor(INS) and doppler velocity log(DVL), and the speed and direction of current is environment parameter. The effectiveness analysis is carried out using circular error probability(CEP) and variance analyze scheme. Also, the effectiveness analysis is utilized for cost-performance analysis considering the cost of commercial INS and DVL sensor. This paper shows the high-level INS and the low-level DVL configure a high price-performance integrated navigation system.

• Journal of Ocean Engineering and Technology
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• 제22권4호
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• pp.106-113
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• 2008

This paper presents an underwater navigation system based on range measurements from a known reference station fixed on the sea bottom or floated at surface with a buoy, for which the system is extended to 3-dimensional coordinates. We formulated a state equation in polar coordinates and constituted an extended Kalman filter for discrete-time implementation of the navigation algorithm. The autonomous underwater vehicle, lSiMl, cruising with a constant speed can estimate its trajectory using just range measurements and additional depth, heading and pitch sensors. Simulation studies were performed to evaluate the underwater navigation of the maneuvering AUV with range measurements. We modulated the sample rate of range measurements to evaluate the effect of the update rate, and changed the initial position error of the AUV to check the robustness to estimation errors. Simulation results illustrates that the extended navigation system provides convergence of the state estimates. The navigation system was conditionally stable when it had initial position errors.

• Journal of Ocean Engineering and Technology
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• 제30권3호
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• pp.214-220
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• 2016

Imaging sonars such as side-scanning sonar or forward-looking sonar are becoming fundamental sensors in the underwater robotics field. However, using sonar images for underwater perception presents many challenges. Sonar images are usually low resolution with inherent speckled noise. To overcome the limited sensor information for underwater perception, we investigated preprocessing methods for sonar images and feature detection methods for a nonlinear scale space. In this paper, we focus on a comparative analysis of (1) preprocessing for sonar images and (2) the feature detection performance in relation to the scale space composition.