• 한국구조물진단유지관리공학회 논문집
• /
• 제18권1호
• /
• pp.174-182
• /
• 2014

건물의 풍진동을 모니터링 하기 위해, 두 개 (이동국과 기준국)의 global positioning system (GPS)에 기반한 종래의 real-time kinematic (RTK) 기법이 널리 적용되고 있다. 그러나 이는 기준국을 위한 공간을 확보하거나 유지 관리하는데 어려움을 겪을 수 있다. 한편, 최근에 하나의 이동국 만을 이용하여 구조물의 움직임을 계측할 수 있는 새로운 virtual reference station (VRS)-RTK 기법이 개발되었으며, 측량 분야에서 널리 사용되고 있다. 본 연구에서는 골조 구조물의 횡방향 구조 응답을 모니터링하기 위한 VRS-RTK 기법의 적용성을 평가하기 위해 단층 골조 모형 (1차 고유진동수 : 1 Hz)과 3층 골조 모형 (1차 고유진동수 : 0.85 Hz)의 자유진동 실험을 수행하였다. GPS에 의해 계측된 변위 및 가속도 응답의 신뢰성을 평가하기 위해, 레이져 변위계와 가속도계가 설치되었으며, 이들로부터 얻은 계측값을 GPS의 계측값과 비교하였다. 또한, 건물의 지속적인 모니터링을 위한 적절한 계측 샘플링 수를 파악하기 위해, 변위 응답에서의 오차가 각기 다른 GPS 샘플링 수 (5, 10, 20 Hz)에서 평가되었다. 실험 결과, GPS으로부터 얻은 변위 및 가속도 응답은 레이져 변위계와 가속계로부터 얻은 응답과 좋은 유사 관계를 가지는 것을 확인하였다. 그리고, GPS 샘플링 수가 증가할수록 변위 오차는 감소하였으며, 3층 실험체에 대해서는 20 Hz의 GPS 샘플링 수로 구조물의 전 모드 성분 (1, 2, 3차 모드)을 검출할 수 있었다.

• 제어로봇시스템학회논문지
• /
• 제8권9호
• /
• pp.818-826
• /
• 2002

Since multipath phenomenon frequently occurs when a Global Positioning System receiver is placed in urban area crowded with large buildings, efficient mitigation of multipath effects is necessary to resolve. In this paper, we propose a new multipath detection technique that is useful in real-time positioning with a general Global Positioning System receiver. The proposed technique is based on a channelwise multipath test statistic that efficiently indicates the degree of fluctuations induced by multipath error. The proposed multipath test statistic is operationally advantageous because it does not require any specialized hardware nor any pre-computation of receiver position, it is directly related to standard $\chi$$^2$-distributions, and it can adjust the detection resolution by increasing the number of successive measurements. Simulation and experiment results verify the performance of the proposed multipath detection technique.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
• /
• pp.194-197
• /
• 1999

In AVL, GIS analyze the information from the vehicles to provide commercial or other value far user. As spatial analysis functions in GIS make a new valuable information using the vehicle's position and geographic object's location, they perform an important roles to improve the management efficiency of vehicles. Most GIS however are used static data for the spatial analysis, so the research area on AVL used dynamic vehicle location has generated unsuitable result. In this study, we use GPS real time tracking data to perform spatial analysis between moving vehicle and static geographic object. The method proposed in this paper considers the driving direction of vehicle and creates the result which is located in forward of vehicle. In this paper, two spatial analysis functions, near and connectivity, are developed.

• Journal of Positioning, Navigation, and Timing
• /
• 제11권4호
• /
• pp.263-268
• /
• 2022

Precise Point Positioning-Real Time Kinematic (PPP-RTK) is a high accuracy positioning method that combines RTK and PPP to overcome the limitations on service coverage of RTK and convergence time of PPP. PPP-RTK provides correction data in the form of State Space Representation (SSR), unlike RTK, which provides measurement-based Observation Space Representation (OSR). Due to this, PPP-RTK has an advantage that it can transmit less data than RTK. So, recently, several techniques for PPP-RTK have been proposed. However, in order to utilize PPP-RTK techniques, performance analysis of these in a real environment is essential. In this paper, we implement the local network PPP-RTK and analyze the positioning performance according to the distance within 100 km from the reference station in Korea. As results of experiment, the horizontal and vertical 95% errors of local network PPP-RTK were 6.25 cm and 5.86 cm or less, respectively.

• Journal of Electrical Engineering and Technology
• /
• 제8권6호
• /
• pp.1431-1438
• /
• 2013

A pack-level battery hardware-in-the-loop simulation (B-HILS) platform is implemented. It consists of dynamic vehicle models using PSAT and multiple control interfaces including real-time 3D driving and GPS mode. In real-time 3D driving mode, user can drive a virtual vehicle using actual drive equipment such as steering wheel and accelerator to generate the cycle profile of the battery. In GPS mode, actual road traffic and terrain effects can be simulated using GPS data while the trajectory is displayed on Google map. In the latter part of the paper, several performance tests of an actual lithium-polymer battery pack are carried out utilizing the developed system. All experiments are conducted as parts of actual development process of a commercial battery pack adopting 2nd generation Prius as a target vehicle model. Through the experiments, the low temperature performance and fuel efficiency of the battery are quantitatively investigated in comparison with the original nickel-metal hydride (NiMH) pack of the Prius.

• 한국측량학회지
• /
• 제22권4호
• /
• pp.401-409
• /
• 2004

GPS를 이용한 컨데이너 모니터링 시스템은 실시간 물류추적 및 관리시스템이라 할 수 있다. GPS는 컨레이너 위치를 정확하고 신속하게 실시간으로 추적할 수 있는 시스템이다. 항만, 공항 등의 시설관리자는 효을적인 화물의 적재, 하역, 보관이 필요하고, 운송업체 또는 화물주는 최적으로 차량을 배차해야 하며, 화물분실, 운송지연 등의 문제를 사전에 예방하거나 대처할 수 있어야 한다. 본 연구에서는 GPS의 측위기법중 실시간 이동 측위 기법을 이용하여 컨테이너의 위치 및 경로를 추적하고, 실시간으로 관측함으로써 상차지에서 하차지까지의 절대위치 및 상대위치를 수치적이고 시각적으로 모니터링하였으며 컨데이너의 이동이나 정지시의 위치 정확도를 분석하였다.

• Journal of Astronomy and Space Sciences
• /
• 제26권1호
• /
• pp.59-74
• /
• 2009

Relative navigation system is presented using GPS measurements from a single-channel global positioning system (GPS) simulator. The objective of this study is to provide the real-time inter-satellite relative positions as well as absolute positions for two formation flying satellites in low earth orbit. To improve the navigation performance, the absolute states are estimated using ion-free GRAPHIC (group and phase ionospheric correction) pseudo-ranges and the relative states are determined using double differential carrier-phase data and singled-differential C/A code data based on the extended Kalman filter and the unscented Kalman filter. Furthermore, pseudo-relative dynamic model and modified relative measurement model are developed. This modified EKF method prevents non-linearity of the measurement model from degrading precision by applying linearization about absolute navigation solutions not about the priori estimates. The LAMBDA method also has been used to improve the relative navigation performance by fixing ambiguities to integers for precise relative navigation. The software-based simulation has been performed and the steady state accuracies of 1 m and 6 mm ($1{\sigma}$ of 3-dimensional difference errors) are achieved for the absolute and relative navigation using EKF for a short baseline leader/follower formation. In addition, the navigation performances are compared for the EKF and the UKF for 10 hours simulation, and relative position errors are mm-level for the two filters showing the similar trends.

• 제어로봇시스템학회논문지
• /
• 제16권2호
• /
• pp.126-133
• /
• 2010

Due to the deployment of various wireless networks originating from CDMA, GSM, and WLAN, it became very convenient to exchange information from one place to another. As compared with the traditional environments for one-way information distribution based on fixed radio frequency bands, the convenient wireless network environments will bring about many changes in positioning technologies based on global navigation satellites. Among the many changes to come, the reconfigurable receiver network is one of the most attractive concepts since it can be tailored to a specific application area among networked robots, formation flying, bridge monitoring, and traffic monitoring. As an initial study to develop a reconfigurable receiver network, this paper deals with the design and implementation of the key elements of the reconfigurable receiver netowork; server, broadcaster, and client. In the designed receiver network, a sever receives and decodes measurements from a reference receiver installed at a known location, a broadcaster processes and transfers the messages from servers to clients and manages connections with servers and clients, a client receives the messages from the broadcaster and performs differential positioning. A real-time experiment result is demonstrated to validate the functionalities of each network element.

• 한국군사과학기술학회지
• /
• 제8권4호
• /
• pp.24-31
• /
• 2005

This paper presents an implementation of a real-time multi-sensor data fusion algorithm for Flight Test Computer. The sensor data consist of positional information of the target from a radar, a GPS receiver and an INS. The data fusion algorithm is designed by the 21st order distributed Kalman Filter which is based on the PVA model with sensor bias states. A fault detection and correction logics are included in the algorithm for bad measurements and sensor faults. The statistical parameters for the states are obtained from Monte Carlo simulations and covariance analysis using test tracking data. The designed filter is verified by using real data both in post processing and real-time processing.

• 한국정밀공학회지
• /
• 제25권10호
• /
• pp.58-66
• /
• 2008

In the development of intelligent vehicles, path tracking of unmanned vehicle is a basis of autonomous driving and automatic navigation. It is very important to find the exact position of a vehicle for the path tracking, and it is possible to get the position information from GPS. However the information of GPS is not the current position but the past position because a vehicle is moving and GPS has a time delay. In this paper, therefore, the moving distance of a vehicle is estimated using a direction sensor and a velocity sensor to compensate the position error of GPS. In the steering control, optimal fuzzy rules for the path tracking can be found through the simulation of Simulink. Real driving experiments show the fuzzy rules are good for the steering control and the position error of GPS is well compensated by the proposed estimation method.