신호차폐 시뮬레이션 환경에서의 통합 GPS/GLONASS 이중차분 상대측위 정확도 분석

이호석(Ho-Seok Lee),박관동(Kwan-Dong Park),김두식(Dusik Kim),손동효(Dong-Hyo Sohn) 한국항해항만학회 2012 한국항해항만학회지 Vol.36 No.6

Although GNSS hardware and software technologies have been steadily advanced, it is still difficult to obtain reliable positioning results in the area with lots of signal blockage. In this study, algorithms for integrated GPS and GLONASS double difference relative positioning were developed and its performance was validated via simulations of signal blockages. We assumed that signal blockages are caused by high-rise buildings to the east, west, and south directions. And then, GPS-only and integrated GPS/GLONASS positioning accuracy was analysed in terms of 2-dimensional positioning accuracies. Compared with GPS-only positioning, the positioning accuracy of integrated GPS/GLONASS improved by 0.3-13.5 meters. 위성항법시스템의 기술발전이 지속적으로 진행되고 있지만 여전히 신호차폐가 빈번히 발생하는 지역에서는 측위정확도 확보에 어려움을 겪고 있다. 이 연구에서는 통합 GPS/GLONASS 이중차분 상대측위 알고리즘을 구현하고 신호차폐 환경의 시뮬레이션을 수행해 그성능을 검증하였다. 동쪽, 서쪽, 남쪽 방향으로 고층건물에 의해 신호차폐가 발생하는 환경을 시뮬레이션 하고 시뮬레이션 상황에 따른 GPS와 GPS/GLONASS의 정확도 평가를 수행하였다. 그 결과, 신호차폐 시뮬레이션 환경에서는 GPS/GLONASS가 GPS에 비해 최소 0.3m에서 최대 13m이상의 수평정확도가 향상되었다.

과포화 확산 방지를 위한 네트워크 단위 앞막힘 예방 제어 전략 개발

김준원,김영찬 대한교통학회 2019 대한교통학회지 Vol.37 No.2

Metropolis such as Seoul are experiencing oversaturation at the signal intersection several times a day. Without suitable measures, the queues increase to such an extent that they can not control, leading to blockage at the intersection reaching the upstream intersection. If there is no appropriate action for oversaturation, the queue becomes uncontrollable and block the upstream intersection. If blockage at intersection occur, it is difficult to cross the intersection in green time, so that the oversaturated situation is spreaded again to the upstream intersection, which causes congestion to the entire network. In this study, to overcome the limitation of the control strategy at oversaturated situation in the COSMOS, we develop the network-wide signal control strategy for preventing blockage at intersection using the front detection system of the COSMOS system. The network-wide signal control strategy for preventing blockage at intersection is a strategy that can immediately respond to the occurrence of the blockage at the intersection and can adjust phase considering the upstream and downstream network traffic conditions. In addition, the control strategy is simplified so that it can be applied to the actual field, and a signal control strategy which is ordered by stages is proposed. Simulation results using the VISSIM Com-interface show that The network-wide signal control strategy for preventing blockage at intersection reduces the average control delay per vehicle by about 30 seconds and the stopping frequency per vehicle by about 2.5 times compared with the conventional TOD signal operation. 서울을 비롯한 국내 대도시에서는 신호교차로에서 하루에도 수없이 과포화상황을 경험하고 있는데, 이때 적절한 조치가 없으면 대기행렬이 제어할 수 없을 정도로 증가해 상류 교차로까지 도달하는 교차로 앞막힘이 발생한다. 현재 국내에서 개발되어 운영 중인 신신호시스템(COSMOS)은 이와같은 과포화상황에 대응하기 위해 앞막힘 예방제어전략을 수행하고 있다. 그러나 신신호시스템의 과포화 전략은 주변 네트워크의 교통상황을 고려하지 않고 해당 교차로 앞막힘 상황만 고려해 앞막힘 발생방향 유입 현시의 녹색시간을 조기종결 함으로써, 오히려 전체 네트워크적인 측면에서 혼잡이 악화될 수 있다. 본 연구에서는 기존 앞막힘 예방제어 전략의 한계를 극복하기 위해 기존 신신호 시스템의 앞막힘 검지체계를 이용한 네트워크 단위 앞막힘 예방 제어전략을 개발하였다. 네트워크 단위 앞막힘 예방 제어전략은 교차로 앞막힘 발생에 즉각적으로 대응할 수 있고 상하류 네트워크 교통상황을 고려하여 현시를 조정할 수 있는 전략이다. 또한 실제 현장에 적용할 수 있도록 제어전략을 간략화 하여 단계별로 규칙화한 신호제어 전략을 제시하였다. VISSIM Com-interface를 이용한 모의실험 결과 기존 TOD (Time of Day) 신호운영에 비해 차량당 평균제어지체가 30초 정도 줄어들었으며 차량당 정지 횟수 역시 2.5회 정도 줄어든 것으로 나타나, 네트워크 단위 앞막힘 예방 제어전략이 과포화상황 개선에 효과적인 것으로 분석되었다.

Analysis of Factors Affecting Performance of Integrated INS/SPR Positioning during GPS Signal Blockage

Kang, Beom Yeon,Han, Joong-hee,Kwon, Jay Hyoun 한국측량학회 2014 한국측량학회지 Vol.32 No.6

Analysis of Factors Affecting Performance of Integrated INS/SPR Positioning during GPS Signal Blockage

강범연,한중희,권재현 한국측량학회 2014 한국측량학회지 Vol.32 No.6

Since the accuracy of Global Positioning System (GPS)-based vehicle positioning system is significantlydegraded or does not work appropriately in the urban canyon, the integration techniques of GPS with InertialNavigation System (INS) have intensively been developed to improve the continuity and reliability ofpositioning. However, its accuracy is degraded as INS errors are not properly corrected due to the GPS signalblockage. Recently, the image-based positioning techniques have been started to apply for the vehicle positioningfor the advanced in processing techniques as well as the increased the number of cars installing the camera. Inthis study, Single Photo Resection (SPR), which calculates the camera exterior orientation parameters using theGround Control Points (GCPs,) has been integrated with the INS/GPS for continuous and stable positioning. The INS/GPS/SPR integration was implemented in both of a loosely and a tightly coupled modes, based on theExtended Kalman Filter (EKF). In order to analyze the performance of INS/SPR integration during the GPSoutage, the simulation tests were conducted with a consideration of factors affecting SPR performance. Theresults demonstrate that the accuracy of INS/SPR integration is depended on magnitudes of the GCP errorsand SPR processing intervals. Additionally, the simulation results suggest some required conditions to achieveaccurate and continuous positioning, used the INS/SPR integration.

Stratospheric Platform Deployment Strategy for Avoiding Satellite Signal Blockage

Hase, Yoshihiro,Shibata, Nobuyuki 통신위성우주산업연구회 2000 Joint Conference on Satellite Communications Vol.2000 No.-

A stratospheric platform is a very large unmanned airship which will be an ideal base station for any kind of wireless system. But there will be a disadvantage of blocking satellite broadcasting and communication links. We have calculated the receiving level degradation and shadowed area on the ground that is dependent on the position stability of the platform and on the configuration of satellite link and platform position. And we will show an eminent reduction of the shadowing effect by choosing and adjusting the nominal platform position. Also the number of houses that remain shadowed and its unavailability due to shadowing are also shown.

Requirements Analysis of Image-Based Positioning Algorithm for Vehicles

Lee, Yong,Kwon, Jay Hyoun 한국측량학회 2019 한국측량학회지 Vol.37 No.5

Requirements Analysis of Image-Based Positioning Algorithm for Vehicles

이용,권재현 한국측량학회 2019 한국측량학회지 Vol.37 No.5

Recently, with the emergence of autonomous vehicles and the increasing interest in safety, a variety of research has been being actively conducted to precisely estimate the position of a vehicle by fusing sensors. Previously, researches were conducted to determine the location of moving objects using GNSS (Global Navigation Satellite Systems) and/or IMU (Inertial Measurement Unit). However, precise positioning of a moving vehicle has lately been performed by fusing data obtained from various sensors, such as LiDAR (Light Detection and Ranging), on-board vehicle sensors, and cameras. This study is designed to enhance kinematic vehicle positioning performance by using feature-based recognition. Therefore, an analysis of the required precision of the observations obtained from the images has carried out in this study. Velocity and attitude observations, which are assumed to be obtained from images, were generated by simulation. Various magnitudes of errors were added to the generated velocities and attitudes. By applying these observations to the positioning algorithm, the effects of the additional velocity and attitude information on positioning accuracy in GNSS signal blockages were analyzed based on Kalman filter. The results have shown that yaw information with a precision smaller than 0.5 degrees should be used to improve existing positioning algorithms by more than 10%