• International Journal of Aeronautical and Space Sciences
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• 제14권4호
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• pp.369-378
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• 2013

This paper presents a vision/LiDAR integrated navigation system that provides accurate relative navigation performance on a general ground surface, in GNSS-denied environments. The considered ground surface during flight is approximated as a piecewise continuous model, with flat and slope surface profiles. In its implementation, the presented system consists of a strapdown IMU, and an aided sensor block, consisting of a vision sensor and a LiDAR on a stabilized gimbal platform. Thus, two-dimensional optical flow vectors from the vision sensor, and range information from LiDAR to ground are used to overcome the performance limit of the tactical grade inertial navigation solution without GNSS signal. In filter realization, the INS error model is employed, with measurement vectors containing two-dimensional velocity errors, and one differenced altitude in the navigation frame. In computing the altitude difference, the ground slope angle is estimated in a novel way, through two bisectional LiDAR signals, with a practical assumption representing a general ground profile. Finally, the overall integrated system is implemented, based on the extended Kalman filter framework, and the performance is demonstrated through a simulation study, with an aircraft flight trajectory scenario.

• 한국항행학회논문지
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• 제27권6호
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• pp.788-797
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• 2023

본 논문은 수직 이착륙 무인 항공시스템의 GPS (global positioning system) 불가 시 대체 항법 시스템으로의 영상보정항법 시스템을 시험하기 위한 검증환경 개발 내용을 소개한다. 개발 중인 영상보정항법 시스템의 시험 및 평가를 위해서는 가상 환경을 활용하는 것이 효율적이지만, 현재 국내에는 적합한 장비가 개발되어 있지 않다. 따라서 제안된 검증환경은 시험 대상 장비의 운용 환경을 모델링 및 시뮬레이션 하여 입력 신호를 생성하고, 출력 신호를 관측함으로써 대상 장비의 성능을 평가할 수 있도록 개발되었다. 연구 과정은 검증환경 요구도 생성, 검증환경 설계에서부터 구성품별 하드웨어 및 소프트웨어 설계, 제작까지 포괄적으로 기술되었다. 이를 바탕으로 제작된 검증환경을 개발 중인 영상기반 보정항법 알고리즘의 성능평가와 시뮬레이션 기반의 사전 비행시험 수행에 활용하였다.

• 한국자동차공학회논문집
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• 제23권1호
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• pp.1-10
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• 2015

In urban area, since multipath and signal attenuations frequently occur due to street trees, street lights and buildings, it is difficult to obtain accurate navigation solution using GPS. As these problems also impact negatively on the INS/GPS coupled system, implementing advanced transportation systems such as autonomous navigation system and Intelligent Transportation System (ITS) become quite hard. For this reason, to alleviate deterioration of navigation system performance in urban area, direction information extraction algorithm using vision system is proposed in this paper. 2D Finite Rate of Innovation (FRI) technique is applied to extract lane edges. The proposed technique is simulated using road images and feasibility of proposed technique is analyzed through the simulation results.

• Journal of Positioning, Navigation, and Timing
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• 제5권3호
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• pp.119-129
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• 2016

This paper presents an integrated navigation system for accurate navigation solution-based safety and convenience services in the vehicular augmented reality (AR)-head up display (HUD) system. For lane-level guidance service, especially, an accurate navigation system is essential. To achieve this, an inertial navigation system (INS)/global positioning system (GPS)/vision/digital map (IGVM) integrated navigation system has been developing. In this paper, the concept of the integrated navigation system is introduced and is implemented based on a multi-model switching filter and vehicle status decided by using the GPS data and inertial measurement unit (IMU) measurements. The performance of the implemented navigation system is verified experimentally.

• 전자통신동향분석
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• 제39권4호
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• pp.1-9
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• 2024

As Advanced Air Mobility (AAM) technologies evolve, ensuring accurate navigation and localization in complex urban airspaces has become crucial. Because the Global Navigation Satellite System (GNSS) is prone to vulnerabilities in urban flight environment, an alternative localization technique is required. This paper examines vision-based localization technologies to enhance GNSS-free navigation. In addition, we explore various geo-referencing studies that utilize pre-existing spatial databases to improve the accuracy of vision-based localization under GNSS-denied conditions. This paper discusses the various types of onboard vision camera sensors, vision-based localization, spatial information databases, feature extraction methods, and matching techniques that contribute to the development of a vision-based localization and geo-referencing system for AAM, ensuring safety and reliability in urban operations.

• 대한전기학회논문지
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• 제38권12호
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• pp.963-970
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• 1989

The navigation problem for a mobile robot is investigated. Specifically, it is proposed that simple guide-marks be introduced and the navigation scheme be generated in conjunction with the guide-marks sensed through camera vision. For autonomous navigation, it was shown that a triple guide-mark system is more effective than a single guide-mark in estimating the position and orientation of mobile robot itself. The navigation system is tested via a mobile robot HERO-I equipped with a single camera in laboratory environment.

• International Journal of Aeronautical and Space Sciences
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• 제12권1호
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• pp.43-56
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• 2011

An integrated system composed of guidance, navigation and control (GNC) system for autonomous proximity operations and the docking of two spacecraft was developed. The position maneuvers were determined through the integration of the state-dependent Riccati equation formulated from nonlinear relative motion dynamics and relative navigation using rendezvous laser vision (Lidar) and a vision sensor system. In the vision sensor system, a switch between sensors was made along the approach phase in order to provide continuously effective navigation. As an extension of the rendezvous laser vision system, an automated terminal guidance scheme based on the Clohessy-Wiltshire state transition matrix was used to formulate a "V-bar hopping approach" reference trajectory. A proximity operations strategy was then adapted from the approach strategy used with the automated transfer vehicle. The attitude maneuvers, determined from a linear quadratic Gaussian-type control including quaternion based attitude estimation using star trackers or a vision sensor system, provided precise attitude control and robustness under uncertainties in the moments of inertia and external disturbances. These functions were then integrated into an autonomous GNC system that can perform proximity operations and meet all conditions for successful docking. A six-degree of freedom simulation was used to demonstrate the effectiveness of the integrated system.

• Journal of Mechanical Science and Technology
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• 제15권8호
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• pp.1097-1107
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• 2001

In this paper, the wall following navigation algorithm of the mobile robot using a mono vision system is described. The key points of the mobile robot navigation system are effective acquisition of the environmental information and fast recognition of the robot position. Also, from this information, the mobile robot should be appropriately controlled to follow a desired path. For the recognition of the relative position and orientation of the robot to the wall, the features of the corridor structure are extracted using the mono vision system, then the relative position, the offset distance and steering angle of the robot from the wall, is derived for a simple corridor geometry. For the alleviation of the computation burden of the image processing, the Kalman filter is used to reduce search region in the image space for line detection. Next, the robot is controlled by this information to follow the desired path. The wall following control scheme by the PD control scheme is composed of two control parts, the approaching control and the orientation control, and each control is performed by steering and forward-driving motion of the robot. To verify the effectiveness of the proposed algorithm, the real time navigation experiments are performed. Through the result of the experiments, the effectiveness and flexibility of the suggested algorithm are verified in comparison with a pure encoder-guided mobile robot navigation system.

• 한국군사과학기술학회지
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• 제14권2호
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• pp.271-280
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• 2011

This paper presents a navigation system based on the tactical communication and vision system in outdoor environments which is applied to unmanned robot for perimeter surveillance operations. GPS errors of robot are compensated by the reference station of C2(command and control) vehicle and WiBro(Wireless Broadband) is used for the communication between two systems. In the outdoor environments, GPS signals can be easily blocked due to trees and buildings. In this environments, however, vision system is very efficient because there are many features. With the feature MAP around the operation environments, the robot can estimate the position by the image matching and pose estimation. In the navigation system, thus, operation modes is switched by navigation manager according to some environment conditions. The experimental results show that the unmanned robot can estimate the position very accurately in outdoor environment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.689-692
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• 1989

In this paper, the navigation problem for a mobile robot is investigated. Specifically, it is proposed that simple guide-marks be introduced and the navigation scheme be generated in conjunction with the guide-marks sensed through camera vision. For autonomous navigation, it was shown that a triple guide-mark system is more effective than a single guide-mark in estimating the position of rho vehicle itself. the navigation system is tested via a mobile robot 'Hero' equipped with a single camera vision.