• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.891-897
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• 2008

GPS can provide precise relative navigation information. But it needs a reference station in a close range and is effected by satellite observation environment. In this paper, we propose INS and Vision sensor integrated system with a known landmark geometry. This system is supposed to overcome problems of GPS only system. Using the proposed method, a relative navigation is available without a GPS reference station. The only need for the proposed system is a landmark image which is drawn on the ground. We conduct simple simulation to check the performance of this method. As a result, we confirm that it can improve the relative navigation information.

• Journal of the Korean Institute of Navigation
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• v.23 no.3
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• pp.1-15
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• 1999

Recently, due to the several factors such as the advent of very large vessels and high-speed vessels, and the increase of the maritime traffic density at sea, the obligation, responsibility and burden of marine officers on duty for the safety of navigation has been highly escalated. Under these situations, if the appropriate and correct navigational information is given to officers at real time by means of certain integrated information processing system, these obligation, burden and danger can be reduced. This paper deals with the study on the development of the Navigational Information Monitoring and Recording System that can give and record the integrated navigational information based on the personal computer system installed on board. To construct this system, the interface unit which changes different signal types of navigational equipments to NMEA 0183 signal format and the application software to show the visual navigational information were developed. In this study, the navigation system of T/S HANBADA in Korea Maritime University was used in order to construct the actual system that can be utilized in other ships, and also the performance test was carried out several times to examine the performance of the system developed. It was proved that all functions of the system as designed worked smoothly through the performance test. Also this system could be operated easily and conveniently by every user.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.2
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• pp.61-71
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• 2018

Existing radio positioning systems have a drawback that the attitude of user's tag is difficult to be determined. Although forward link angle of arrival (FLAOA) technology that uses measurements of array antenna arranged in a tag among the angle of arrival (AOA) technologies can estimate attitude and positioning of tags, it cannot extend the estimated results into three-dimensional (3D) results due to complex non-linear model displayed because of the effects of 3D positioning and attitude in tags. This paper proposed a radio navigation technique that determines 3D attitude and positioning via FLAOA / time of arrival (TOA) integration. According to the order of determining attitude and positioning, two integration techniques were proposed. To analyze the performance of the proposed technique, MATLAB-based simulations were used to verify the performance. The simulation results showed that the first proposed method, TOA-FLAOA integrated technique, showed about 0.15 m of positioning error, and $2-3^{\circ}$ of attitude error performances regardless of the positioning space size whereas the second method, differenced FLAOA-TOA integrated technique, revealed a problem that a positioning error became larger as the size of the positioning space became larger.

• Journal of Ocean Engineering and Technology
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• v.19 no.5 s.66
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• pp.71-77
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• 2005

This paper presents an integrated underwater navigational algorithm for unmanned underwater vehicles, using additional two-range transducers. This paper proposes a measurement model, using two range measurements, to improve the performance of an IMU-DVL (inertial measurement unit - Doppler velocity log) navigation system for long-time operation of underwater vehicles, excluding DVL measurement. Extended Kalman filter was adopted to propagate the error covariance, to update the measurement errors, and to correct the state equation when the external measurements are available. Simulation was conducted with the 6-d.o.f nonlinear numerical model of an AUV in lawn-mowing survey mode, at current flaw, where the velocity information is unavailable. Simulations illustrate the effectiveness of the integrated navigation system, assisted by the additional range measurements without DVL sensing.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.361-368
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• 2022

An indoor navigation system that utilizes long-term evolution (LTE) signals has the benefit of no additional infrastructure installation expenses and low base station database management costs. Among the LTE signal measurements, received signal strength (RSS) is particularly appealing because it can be easily obtained with mobile devices. Propagation channel models can be used to estimate the position of mobile devices with RSS. However, conventional channel models have a shortcoming in that they do not discriminate between line-of-sight (LOS) and non-line-of-sight (NLOS) conditions of the received signal. Accordingly, a previous study has suggested separated LOS and NLOS channel models. However, a method for determining LOS and NLOS conditions was not devised. In this study, a machine learning-based LOS/NLOS classification method using RSS measurements is developed. We suggest several machine-learning features and evaluate various machine-learning algorithms. As an indoor experimental result, up to 87.5% classification accuracy was achieved with an ensemble algorithm. Furthermore, the range estimation accuracy with an average error of 13.54 m was demonstrated, which is a 25.3% improvement over the conventional channel model.

• Journal of Advanced Navigation Technology
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• v.23 no.3
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• pp.228-236
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• 2019

Recently, multi-sensor integration techniques have been actively studied to obtain reliable and accurate navigation solution in GPS (Global Positioning System)-denied harsh environments such as urban canyons, tunnels, and underground roads. In this paper, we propose a low-cost ultrasonic-speedometer utilizing the characteristics of the ultrasonic propagation. An efficient integrated INS (inertial navigation system)/ultrasonic-speedometer navigation system is also proposed to improve the accuracy of positioning in GPS-denied environments. To evaluate the proposed system, car experiments with field-collected measurements were performed. By the experiment results, it was confirmed that the proposed INS/ultrasonic-speedometer system bounds the positioning error growth effectively even though GPS signal is blocked more than 10 seconds and a low-cost MEMS IMU (micro electro mechanical systems inertial measurement unit) is utilized.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.4
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• pp.281-290
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• 2021

For successful operations of an airborne Active Electronically-Scanned Array (AESA) radar, which has various advantages over traditional radar systems, accurate and robust navigation is critical. This paper discusses a study on the performance analysis of an integrated navigation based on the Embedded GPS/INS (EGI) system for an aircraft equipped with an AESA radar. The models for generating the inputs for the GPS/IMU are developed. A navigation filter for a loosely-coupled GPS/IMU system is constructed. Overall navigation performance assessment procedure using a six degree of freedom aircraft simulator - along with the GPS/IMU models and the navigation filter - is introduced. The steps of the performance analysis procedure are explained using a comprehensive case study.

• Journal of Korea Multimedia Society
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• v.24 no.12
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• pp.1589-1597
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• 2021

Due to the low output rate and time delay of vehicle's navigation results, the electro-optical tracking system(EOTS) cannot estimate accurate target positions. If an inertial measurement unit(IMU) is additionally mounted into the EOTS and inertial navigation system(INS) is constructed, the high navigation output rate can be obtained. And the time-delay can be compensated by using the augmented Kalman filter. An accurate initial attitude is required in order to have accurate navigation outputs. In this paper, an attitude determination algorithm is proposed using the augmented Kalman filter in order to compensate measurement delay of the EOTS and have accurate initial attitude. The proposed initial attitude determination algorithm consists of an augmented Kalman filter, an INS, and an integrated Kalman filter. The augmented Kalman filter compensates the time-delay of the vehicle's navigation results and the integrated Kalman filter estimates the navigation error of the INS. In order to evaluate performance of the proposed algorithm, vehicle's navigation outputs and IMU measurements were generated using sensors' model-based measurement generator and initial attitude estimation errors of the proposed algorithm and the conventional algorithm without the augmented Kalman filter were compared for the generated measurements. The evaluation results show that the proposed algorithm has better accuracy.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.58-58
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• 2016

This study aims to enhance Korea's competitiveness by taking the lead in the international standardization and relevant global market. This is to be achieved by performing the role of First Mover through the resolute investment from Fast Follower that is servile to the decision of the organization in the e-Navigation strategy that has been promoted by the IMO. The study methodology is an integrated approach. It is established by modelling LSCM G2B2C2 Platform in maritime safety/security logistics and applied to the enhancement of maritime safety/security in global LSCM. This paper externally contributes to the reduction of world maritime accidents and exalt the national prestige; internally, the enhancement of the national competitiveness through the improvement of shipping port logistics and others. These eventually contribute to Korea's economic development that is combined by both theory and practice and of practical use of the integrated approach.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.12a
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• pp.263-266
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• 2001

It has been integrated into several navigation systems. This paper shows that system recognizes difficult indoor roads and open area without any specific mark such as painted guide line or tape. In this method, Robot navigates with visual sensors, which uses visual information to navigate itself along the road. An Artificial Neural Network System was used to decide where to move. It is designed with USB web camera as visual sensor.