• Title/Summary/Keyword: inertial alignment system

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Performance Analysis of Self-Alignment in the Temperature Stabilizing State of Inertial Navigation System (관성항법장치 온도 안정화 상태에서의 초기정렬 성능분석)

  • Kim, Cheon-Joong;Lyou, Joon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.8
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    • pp.796-803
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    • 2011
  • It is called self-alignment or initial alignment that INS(Inertial Navigation System) is aligned using the measurements from the inertial sensors as an accelerometer and a gyroscope and the inserted reference navigation information in the stop state. The main purpose of self-alignment is to obtain the initial attitude of INS. The accuracy of self-alignment is determined by the performance grade of the used inertial sensors, especially horizontal attitude accuracy by the horizontal accelerometer and vertical attitude accuracy by the E-axis gyroscope. Therefore the uncertain errors in the inertial sensors cause the performance of self-alignment to degrade. In this paper, we analyze theoretically and through a simulation how the errors of inertial sensors in the temperature stabilizing state, one of the uncertain errors, affect the accuracy of self-alignment.

Psi Angle Error Model based Alignment Algorithm for Strapdown Inertial Navigation System (Psi각 오차모델 기반 스트랩다운 관성 항법 시스템의 정렬 알고리즘)

  • Park, Sul-Gee;Hwang, Dong-Hwan;Lee, Sang-Jeong
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.2
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    • pp.183-189
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    • 2011
  • An alignment algorithm for strapdown inertial navigation systems is proposed, in which the psi angle error model is utilized. The proposed alignment algorithm is derived from the Psi angle error model which has been widely used in real-time navigation systems. The equation for expecting steady state alignment error is also derived. The proposed algorithm was verified through real-time experiments. Experimental results show that the proposed algorithm can be used in the inertial navigation system and GNSS/INS integrated navigation system to get an initial attitude of the vehicle.

Alignment error analysis of KAL KE007 inertial navigation system

  • Park, Chan-Ung
    • 제어로봇시스템학회:학술대회논문집
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    • 1992.10a
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    • pp.564-566
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    • 1992
  • It is tragic that the Korean Airline Boing 747, KE007, wandered hundreds of miles off course into Soviet airspace and was shot down on September 1, 1983. The exact cuases are not known yet. Thus, speculation centers on human error or faulty procedure of three Litton LTN-72R inertial navigation systems(INS) with which the KAL KE007 was equipped. The inertial platform must be aligned before the INS can be used as a precision inertial navigation system. This analysis checks a possibility that the navigation errors are caused by a wrong INS alignment procedure assuming it is done at Anchorage. Possible causes for the navigational position error, such as alignment errors and gyro drift errors, are analyzed through inertial navigation system error prapagation simulations. A set of misalignment angle is estimated to determine what degree of alignment errors are required to cause the navigation error assuming that the accident is caused by the INS misalignment.

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A Study on Performance Improvement Method of Fixed-gain Self-alignment on Temperature Stabilizing State of Accelerometers (가속도계 온도안정화 상태에서 고정이득방식 자체정렬의 성능개선 방법에 대한 연구)

  • Lee, Inseop
    • Journal of the Korea Institute of Military Science and Technology
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    • v.19 no.4
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    • pp.435-442
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    • 2016
  • For inertial navigation systems, initial information such as position, velocity and attitude is required for navigation. Self-alignment is the process to determine initial attitude on stationary condition using inertial measurements such as accelerations and angular rates. The accuracy of self-alignment is determined by inertial sensor error. As soon as an inertial navigation system is powered on, the temperature of accelerometer rises rapidly until temperature stabilization. It causes acceleration error which is called temperature stabilizing error of accelerometer. Therefore, temperature stabilizing error degrades the alignment accuracy and also increases alignment time. This paper suggests a method to calculate azimuthal attitude using curve fitting of horizontal control angular rate in fixed-gain self-alignment. It is verified by simulation and experiment that the accuracy is improved and the alignment time is reduced using the proposed method under existence of the temperature stabilizing error.

Numerical Analysis of Relative Orbit Control Strategy for CANYVAL-X Mission

  • Lee, Youngro;Park, Sang-Young;Park, Jae-Pil;Song, Youngbum
    • Journal of Astronomy and Space Sciences
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    • v.36 no.4
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    • pp.235-248
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    • 2019
  • This paper suggests a relative orbit control strategy for the CubeSat Astronomy by NASA and Yonsei using Virtual Telescope Alignment eXperiment (CANYVAL-X) mission whose main goal is to demonstrate an essential technique, which is an arrangement among two satellites and a specific celestial object, referred to as inertial alignment, for a next-generation virtual space telescope. The inertial alignment system is a relative orbit control system and has requirements for the relative state. Through the proposed orbit control strategy, consisting of separation, proximity keeping, and reconfiguration, the requirements will be satisfied. The separation direction of the two CubeSats with respect to the orbital plane is decided to provide advantageous initial condition to the orbit controller. Proximity keeping is accomplished by differential atmospheric drag control (DADC), which generates acceleration by changing the spacecraft's effective cross section via attitude control rather than consuming propellant. Reconfiguration is performed to meet the requirements after proximity keeping. Numerical simulations show that the requirements can be satisfied by the relative orbit control strategy. Furthermore, through numerical simulations, it is demonstrated that the inertial alignment can be achieved. A beacon signal had been received for several months after the launch; however, we have lost the signal at present.

Design of transfer alignment algorithm in ship of horizontal axis attitude motion (수평축 자세운동이 있는 배에서의 전달정렬 알고리즘 설계)

  • Song, Ki-Won;Jeon, Chang-Bae;Kim, Hyun-Baek;Yoo, Jun
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.672-675
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    • 1996
  • This paper presents algorithm including Kalman filter for transfer alignment of velocity and quaternion matching method, when master inertial navigation system is a gimbled type and slave inertial navigation system is a strapdown type on a cruising ship which is naturally in motion of horizontal axis attitude. And relative attitudes are considered on a measurement equation for quaternion matching between master INS and slave INS.

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Alignment and Navigation of Inertial Navigation and Guidance Unit using Inertial Explorer Software (Inertial Explorer 소프트웨어를 이용한 관성항법유도장치 정렬 및 항법계산)

  • Kim, Jeong-Yong;Oh, Jun-Seok;Roh, Woong-Rae
    • Aerospace Engineering and Technology
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    • v.9 no.1
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    • pp.50-59
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    • 2010
  • In this paper, the alignment and navigation results by INGU(Inertial Navigation and Guidance Unit) onboard software and by Inertial Explorer which is a post-processing software specialized for IMU(Inertial Measurement Unit) are compared for identification of inertial sensor error models and estimation of alignment and navigation errors for KSLV-I INGU. For verification of the IMU error estimated by Kalman Filter of Inertial Explorer, the covariance parameters of inertial sensor error model state are identified by using stochastic error model of inertial sensors estimated by Allan variance and the alignment and navigation test with static condition and the land navigation test with dynamic condition are carried out. The validity of inertial sensor model for KSLV-I INGU is verified by comparison the alignment and navigation results of INGU on-board software and Inertial Explorer.

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.

An initial coarse alignment algorithm for strapdown inertial navigation system (스트랩다운 관성항법시스템의 초기 개략정렬 알고리즘)

  • 박찬국;김광진;이장규
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.856-859
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    • 1996
  • In this paper, a coarse alignment algorithm for strapdown inertial navigation system is proposed and evaluated analytically. The algorithm computes roll and pitch angles of the vehicle using accelerometer outputs, and then determines yaw angle with gyro outputs. It is referred, as two-step coarse alignment in this work. With the geometric relation between sensor outputs and roll, pitch and yaw angles, the algorithm error is analytically derived and compared with the previous coarse alignment algorithm introduced by Britting. The results show that the proposed two-step coarse alignment algorithm has better performance for pitch angle computation.

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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.