• Title/Summary/Keyword: Precision Navigation

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Comparison of Ionospheric Spatial Gradient Estimation Methods using GNSS (GNSS를 이용한 전리층 기울기 추정 방법 비교)

  • Jeong, Myeong-Sook;Kim, Jeong-Rae
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.15 no.2
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    • pp.18-24
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    • 2007
  • The high ionospheric spatial gradient during ionospheric storm is the most concern when applying GNSS(Global Navigation Satellite System) augmentation systems for aircraft precision approach. Since the ionospheric gradient level depends on geographical location as well as the storm, understanding the ionospheric gradient statistics over a specific regional area is necessary for operating the augmentation systems. This paper compares three ionosphere gradient computation methods, direct differentiation between two receivers' ionospheric delay signal for a common satellite, derivation from a grid ionosphere map, and derivation from a plate ionosphere map. The plate map method provides a good indication on the gradient variation behavior over a regional area with limited number of GNSS receivers. The residual analysis for the ionosphere storm detection is discussed as well.

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Extension and Implementation of Iconic Stereotype for GNSS Application in the UML Class Diagram

  • Wang Bo;No, Hye-Min;Yoo, Cheol-Jung;Chang, Ok-Bae
    • Proceedings of the Korean Information Science Society Conference
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    • 2003.04c
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    • pp.136-138
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    • 2003
  • UML cannot meet all the requirements offered in different software system for diverse application domain. GNSS (Global Navigation Satellite System) application domain is an especial environment that requires precise measurement and precision calculation of real-world geographical entities with the help of GPS (Global Position System) in both temporal and spatial factor. Therefore in the paper new extended iconic stereotypes for better modeling GNSS application in the UML Diagram are proposed, and the implementation of a program called StereotypeCreator, which is able to create iconic stereotypes used in one of the most popular visual modeling tools for software development, Rational Rose, will be also proposed.

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Resonant Loop Design and Performance Test for a Torsional MEMS Accelerometer with Differential Pickoff

  • Sung, Sang-Kyung;Hyun, Chul;Lee, Jang-Gyu
    • International Journal of Control, Automation, and Systems
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    • v.5 no.1
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    • pp.35-42
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    • 2007
  • This paper presents an INS(Inertial Navigation System) grade, surface micro-machined differential resonant accelerometer(DRXL) manufactured by an epitaxially grown thick poly silicon process. The proposed DRXL system generates a differential digital output upon an applied acceleration, in which frequency transition is measured due to gap dependent electrical stiffness change. To facilitate the resonance dynamics of the electromechanical system, the micromachined DRXL device is packaged by using the wafer level vacuum sealing process. To test the DRXL performance, a nonlinear self-oscillation loop is designed based on the extended describing function technique. The oscillation loop is implemented using discrete electronic elements including precision charge amplifier and hard feedback nonlinearity. The performance test of the DRXL system shows that the sensitivity of the accelerometer is 24 Hz/g and its long term bias stability is about 2 mg($1{\sigma}$) with dynamic range of ${\sigma}70g$.

Moving Path following and High Speed Precision Control of Autonomous Mobile Robot Using Fuzzy (퍼지를 이용한 자율 이동 로봇의 이동 경로 추종 및 고속 정밀 제어)

  • 이원호;이형우;김상헌;정재영;노태정
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2004.10a
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    • pp.207-210
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    • 2004
  • 일반적인 이동 로봇의 주된 관심은 경로 생성과 생성된 경로 추종에 있다. 그러나 일부 고속의 이동성이 필요로 하는 로봇의 경우 동역학적 제한 조건이 존재하며, 이러한 제한 조건내에서 원하는 움직임에 대한 제어가 요구된다. 본 논문에서 환경 지도를 가지고 있지 않은 상태, 즉 미지의 환경에서 이동 로봇의 경로 추종에 있어서 빠른 이동시에 발생할 수 있는 이동 로봇의 미끄러짐이나 전복 현상을 막기 위해 이동 로봇의 동역학적 제한 조건을 퍼지 논리를 이용하여 기준 속도를 변화시켜 안전하고 빠른 경로 추종 성능을 얻고자 하였다. 특히, 라인 추종 이동 로봇을 모델링하여 실시간으로 변화하는 목표점에 대한 추종 제어기를 설계하고 퍼지 최적 속도 제한 제어기를 통해 연속적으로 변화하는 라인에 대해서 지능적으로 로봇이 변화하는 라인에 대해서 지능적으로 로봇의 속도를 제한하여 안정적인 추종 성능을 발휘함을 확인하였다.

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A Real-Time NDGPS/INS Navigation System Based on Artificial Vision for Helicopter (인공시계기반 헬기용 3차원 항법시스템 구성)

  • Kim, Jae-Hyung;Lyou, Joon;Kwak, Hwy-Kuen
    • Journal of the Korea Institute of Military Science and Technology
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    • v.11 no.3
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    • pp.30-39
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    • 2008
  • An artificial vision aided NDGPS/INS system has been developed and tested in the dynamic environment of ground and flight vehicles to evaluate the overall system performance. The results show the significant advantages in position accuracy and situation awareness. Accuracy meets the CAT-I precision approach and landing using NDGPS/INS integration. Also we confirm the proposed system is effective enough to improve flight safety by using artificial vision. The system design, software algorithm, and flight test results are presented in details.

An Empirical case Study on the Improvement of Surveillance Systems in performing Circling Approach at the airport (선회접근용 활주로 감시도구의 개선에 관한 실증적 사례 연구)

  • Yang, Han-Mo;Shin, Hyon-Sam
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.14 no.4
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    • pp.110-119
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    • 2006
  • This research was conducted with a view to enhance the efficiency of the preventive tool which provide pilots and controllers with proper and timely safety alerts while conducting circling approach at the airport where surrounding terrains becomes threat to safe operation of flight around airport.

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Study on Performance Analysis Technique of GPS Receiver According to Vehicle Attitude Change (항체 자세 변화에 따른 GPS 수신기의 성능분석 기법 연구)

  • Yoo Ki-Jeong
    • Journal of the Korea Institute of Military Science and Technology
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    • v.7 no.2 s.17
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    • pp.13-21
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    • 2004
  • GPS is widely used in various applications since GPS receivers are capable of measuring precise position and velocity in any weather condition for a relatively low cost. However, GPS requires more than four simultaneously visible GPS satellites for optimal performance. In high-motion, high-attitude-changing applications, there exist some situations where less than four satellites are visible or where the dilution of precision (DOP) is high. In this paper, we propose a simulation algorithm that predicts the performance of GPS navigation according to changes in vehicle attitude. We have compared simulation results with experimental results, where simulation results of the proposed algorithm are shown to closely match actual experimental data. This algorithm could be used to predict GPS navigational performance and to determine optimal GPS antenna position.

Design of a Two-dimensional Attitude Determining GPS Receiver (이차원 자세 측정용 GPS 수신기 설계)

  • 손석보;박찬식;이상정
    • Journal of the Korea Institute of Military Science and Technology
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    • v.3 no.2
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    • pp.131-139
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    • 2000
  • A design of CPS attitude determination system is described in this paper. The designed system is a low cost high precision 24 channel single frequency GPS(Global Positioning System) receiver which provides a precise absolute heading and pitch (or roll) as well as a position. It uses commercial chip-set and consists of two RF parts, two signal-tracking parts, a processor, memory parts and I/Os. In order to determine precise attitude, accurate carrier phase measurements and an efficient integer ambiguity resolution method are required. To meet these requirements, a PLL (Phase Locked Loops) is designed, and an algorithm called ARCE (Ambiguity Resolution with Constraint Equation) is adopted. The hardware and software structure of the system will be described, and the performance evaluated under various conditions will be presented. The test results will promise that more reliable navigation system be possible because the system provides all navigational information such as position, velocity, time and attitude.

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Multi-information fusion based localization algorithm for Mars rover

  • Jiang, Xiuqiang;Li, Shuang;Tao, Ting;Wang, Bingheng
    • Advances in aircraft and spacecraft science
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    • v.1 no.4
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    • pp.455-469
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    • 2014
  • High-precision autonomous localization technique is essential for future Mars rovers. This paper addresses an innovative integrated localization algorithm using a multiple information fusion approach. Firstly, the output of IMU is employed to construct the two-dimensional (2-D) dynamics equation of Mars rover. Secondly, radio beacon measurement and terrain image matching are considered as external measurements and included into the navigation filter to correct the inertial basis and drift. Then, extended Kalman filtering (EKF) algorithm is designed to estimate the position state of Mars rovers and suppress the measurement noise. Finally, the localization algorithm proposed in this paper is validated by computer simulation with different parameter sets.

A Study on the Crawling and Classification Strategy for Local Website (로컬 웹사이트의 탐색전략과 웹사이트 유형분석에 관한 연구)

  • Hwang In-Soo
    • Journal of Information Technology Applications and Management
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    • v.13 no.2
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    • pp.55-65
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    • 2006
  • Since the World-Wide Web (WWW) has become a major channel for information delivery, information overload also has become a serious problem to the Internet users. Therefore, effective information searching is critical to the success of Internet services. We present an integrated search engine for searching relevant web pages on the WWW in a certain Internet domain. It supports a local search on the web sites. The spider obtains all of the web pages from the web sites through web links. It operates autonomously without any human supervision. We developed state transition diagram to control navigation and analyze link structure of each web site. We have implemented an integrated local search engine and it shows that a higher satisfaction is obtained. From the user evaluation, we also find that higher precision is obtained.

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