• Title, Summary, Keyword: Initial alignment

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Design of SDINS Rapid Initial Alignment Technique Robust to the Pyro-shock in Multi-Launch Rocket System (연속발사 충격에 강인한 SDINS 신속 초기정렬기법 설계)

  • Lee, Hyung-Sub;Han, Kyung-Jun;Lee, Sang-Woo;Yu, Myeong-Jong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.6
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    • pp.1038-1044
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    • 2016
  • In this paper, a SDINS(Strapdown Inertial Navigation System) rapid initial alignment technique robust to the pyro-shock in multi-launch rocket system is proposed. The proposed method consists of three steps. Firth, transfer alignment is performed to estimate misalignment between MINS(Master INS) and SINS(Slave INS), and the estimated misalignment is written in the memory when transfer alignment is completed. Next, the pre-filtering process is performed to get rid of the acceleration error induced by launcher vibration. Finally, the horizontal alignment is performed to compensate misalignment variation caused by pyro-shock. We verified the performance of the proposed alignment method comparing with the conventional transfer alignment method. The simulation shows that the proposed initial alignment technique improves alignment performance.

Performance Analysis in Disturbance on Initial Alignment of Laser Inertial Navigation System Using Unscented Kalman Filter (UKF를 적용한 레이저 관성항법장치의 외란에 대한 초기정렬 성능분석)

  • Oh, Juhyun
    • Journal of the Korea Institute of Military Science and Technology
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    • v.17 no.4
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    • pp.537-543
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    • 2014
  • RLG(Ring Laser Gyroscope) is a main device of LINS(Laser Inertial Navigation System). RLG has the lock-in region in which there is no output signal. To alleviate the lock-in problem, a mechanical oscillation, the dither motion, is applied on RLG. A LPF(Low Pass Filter) is usually used on the output of RLG and accelerometer to remove the noise that is made by the dither motion. When the LINS is induced the disturbance during the initial alignment, it takes more time on alignment due to the use of the LPF and a fixed gain controller. In this paper, an initial alignment using UKF(Unscented Kalman Filter) is designed and analysed. Analysis include comparison between conventional initial alignment loop using fixed gain type controller and proposed initial alignment using UKF. Moreover, Disturbance inducing test results are demonstrated.

Design and Evaluation of INS Initial Alignment under Vibration Environment of Aircraft Run-up (항공기 Run-Up 진동 환경에서의 관성항법장치 초기 정렬 방법 설계 및 평가)

  • Yu, Haesung;Lee, Inseop;Oh, JuHyun;Kim, CheonJoong;Park, Heung-won
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.7
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    • pp.691-698
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    • 2015
  • Inertial Navigation Systems (INS) are widely used as the main navigation device for aircraft. To get the initial attitude, the INS requires the initial alignment before navigation starts. An aircraft also needs an engine test procedure that causes some vibrations before flight. An INS can't be aligned in a vibration environment so the initial alignment is performed before the aircraft engine test. Therefore, the initial alignment time of an INS has been a major factor in limiting an aircraft's takeoff response time. In this paper, we designed an initial alignment algorithm that can be executed even in disturbances such as aircraft run-up. We demonstrated verification of the algorithm that is embedded on the real INS and testing methods to evaluate the alignment of the INS. We also analyzed the test results of the proposed initial alignment algorithm that is performed during a real aircraft run-up.

A Study of An Initial Alignment Method of Underwater Vehicle Dropped from Aircraft (항공기에서 투하되는 수중운동체의 초기정렬기법 연구)

  • 류동기;김삼수
    • Journal of the Korea Institute of Military Science and Technology
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    • v.6 no.1
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    • pp.21-29
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    • 2003
  • The Strap Down Inertial Measurement Unit(SDIMU) is recently used for the sensor package of the modern underwater vehicles such as torpedoes and unmanned underwater-vehicles. For using SDIMU, an initial alignment must be carried out before the fire or navigation stage. The general initial alignment methods require that a mother vehicle Is a stationary condition or the Inertial Navigation System(INS) of vehicle is received the specific of data navigation from the mother vehicle. But an underwater vehicle dropped from aircraft is hard to satisfy above both necessary conditions of the general initial alignment. So, we suggest a new strap down initial alignment method of an underwater vehicle dropped from aircraft without using any aided sensors. The highlight point of this method is that a period of initial alignment is not before the fire but during running stage to fix alignment error. And we verify it by analyzing various data of S/W simulations, Hardware In the Loop Simulation(HILS) tests and sea trials.

Rapid Initial Alignment Method of Inertial Navigation System Using Adaptive Time Delay Compensation (적응형 시간지연 보상을 통한 관성항법장치 급속초기정렬기법)

  • Lee, Hyung-Sub
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.3
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    • pp.433-439
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    • 2018
  • In this paper, a SDINS(strapdown inertial navigation system) rapid initial alignment technique with adaptive time delay compensation is proposed. The proposed method consists of two steps. In first step, misalignment and data latency are estimated by conducting pre-transfer alignment. Then, hybrid alignment is designed to rapidly find the misalignment changes induced by pyro-shock. To improve the performance of hybrid alignment, adaptive time delay compensation method is suggested. We verify the performance improvement of the proposed alignment scheme comparing with the conventional transfer alignment method by van test. The test result shows that the proposed alignment technique improves alignment performance.

Performance Analysis on the Initial Alignment of Laser Inertial Navigation System (레이저 관성항법장치 초기정렬 성능 분석)

  • Kim, Hyun-Seok;Kim, Cheon-Joong;Lee, Tae-Gyoo
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.5
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    • pp.622-635
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    • 2009
  • Laser Inertial Navigation System(LINS) consists of Ring Laser Gyroscopes(RLG) and accelerometers. RLG has a lock-in region in which there is zero output for input angular rates less than about 0.1deg/sec. The lock-in region is generated by the imperfect mirrors in RLG. To avoid the lock-in region, a sinusoidal motion called dither motion is applied on RLG. Therefore this dither motion is measured by RLG/accelerometer even if at a stop state. In this situation, the performance on the initial alignment of LINS can be degraded. In this paper, we analyze the performance on the initial alignment of LINS theoretically and experimentally. Analysis results include how dither motion, the pre-filter and the corner frequency in alignment loop affects the performance on the initial alignment of LINS.

CLINICAL CONSIDERATION IN THE CHOICE OF ALIGNMENT ARCHES (치아배열을 위한 교정용 탄선의 선택에 대한 고찰)

  • Park, E. Woong;Kim, Sang Cheol
    • The korean journal of orthodontics
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    • v.19 no.3
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    • pp.79-86
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    • 1989
  • The wires for initial alignment purposes require a combination of excellent strength, excellent springiness, and a long rang of action. The variables in selecting appropriate arches for alignment are the arch wire material, its diameter, and the distance between attachments. The principle that there should be 0.02 inch clearance for initial wires means that an .016 diameter wire is the largest that should be considered for initial alignment in the .018 slot system. The three major possibilities for alignment arches are multistranded steel wires, nickel-titanium wires, and single-stranded steel wires with loops. The excellent choice for initial alignment in .018 bracket is .014 steel wire with loops.

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In-Flight Alignment Algorithm Using Uplinked Radar Data Including Time Delay

  • Park, Chan-Ju;Kim, Heun-Beik;Song, Gi-Won
    • 제어로봇시스템학회:학술대회논문집
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    • pp.56.1-56
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    • 2001
  • Initial attitude error is one of the large error sources in the navigation errors of SDINS. And it is important to decide the initial attitude of SDINS. The method, like a self-alignment or a transfer alignment method, is required to a precise INS. If we do not have a precise INS, we should get large attitude error. After performing the initial alignment, a vehicle has the initial attitude error. Therefore, it results in navigation error due to the initial attitude error. But, if we use position information during flight, we could estimate and compensate a vehicle attitude error. So, we can maintain a precise attitude in spite of existing the initial attitude error. Using the uplinked position information from a land-based radar system, the new algorithm estimates the attitude of the SDINS during flight ...

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In - Motion Alignment Method for a Low - cost IMU based GPS/INS System

  • Kim, Jeong-Won;Oh, Snag-Heon;Hwang, Dong-Hwan
    • 제어로봇시스템학회:학술대회논문집
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    • pp.990-994
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    • 2003
  • When the low cost IMU is used, the result of the stationary self alignment is not suitable for navigation. In this paper, an in-motion alignment method is proposed to obtain an accurate initial attitude of a low cost IMU based GPS/INS integration system. To design Kalman filter for alignment, large heading error model is introduced. And then Kalman filter is designed to estimate initial attitude error as the indirect feedback filter. In order to assess performance of the alignment method, computer simulations are carried out. The simulation results show that initial attitude error rapidly reduces.

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In-Flight Alignment of SDINS without Initial Heading Information (초기 기수각 정보가 필요 없는 SDINS의 운항중 정렬)

  • 홍현수;이장규;박찬국
    • Journal of Institute of Control, Robotics and Systems
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    • v.8 no.6
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    • pp.524-532
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    • 2002
  • This paper presents a new in-flight alignment method for an SDINS under large initial heading error. To handle large heading error, a new attitude error model is introduced. The attitude errors are divided into heading error and leveling errors using a newly defined horizontal frame. Some navigation error dynamic models are derived from the attitude error model for indirect feedback filtering of the in-flight alignment system. A Kalman filter with Position measurement is designed to estimate navigation errors as the indirect feedback filter Simulation results show that the proposed in-flight alignment method reduces the heading error very quickly from more than 40deg to about 5deg so as to apply a refined navigation filter. The total alignment process including leveling mode and navigation mode in addition to the proposed one allows large initial values not only in heading error but also in leveling errors.