• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.11
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• pp.921-933
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• 2018

There is a method to enhance the pure navigation performance of INS(Inertial Navigation System) through the rotation of inertial measurement unit to compensate error sources of inertial sensors each other and that INS using this principle of operation is called rotational INS. In this paper, the exact error analysis of rotational INS based on ring laser gyro considering the coupling effect with gravity and earth rate is performed to evaluate the navigation performance by inertial sensor error sources. And error analysis and performance evaluation result confirmed by modelling and simulation is also proposed in this paper.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.5
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• pp.502-510
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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 0.1deg/sec. The lock-in region is generated by the imperfect mirrors in RLG. To avoid the lock-in region, sinusoidal motion which is called dither motion is applied on RLG. Therefore without the fault in LINS, the dither motion must be measured by RLG/accelerometer. In this paper, we propose the method to detect the fault of LINS through checking out whether or not the dither motion is always measured by RLG/accelerometer using the Fast Fourier Transformation(FFT) on the real time. The feasibility of the fault detection method proposed in this paper is verified through the stationary and van test.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.8
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• pp.788-795
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• 2011

In this paper, we present the requirements specification to develop the small ring laser gyroscope(RLG) which is applicable to the medium-grade inertial navigation system(INS) widely used as a main navigation system. To this end, first we analyse the performance specifications of RLG which is needed to configure the medium-grade INS and then we present the design results of RLG to meet the performance specifications, based on the overseas technology survey and the theoretical analysis. It is also shown in this paper what technology is required to develop a small RLG.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.2
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• pp.134-141
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• 2013

This paper explores a real-time system implementation to couple tightly StrapDown Inertial Navigation System(SDINS) and Global Positioning System(GPS) mounted on the aircraft. When implementing the SDINS/GPS coupled system in real-time processor, we have to deliberate SDINS's unique characteristics based on the ring laser gyro, and besides, lever-arm, measurements, and error compensation method. The novel modeling method is applied to system the misalignment error term of gyro to estimate the cumulative heading attitude errors while the aircraft banking to turn repeatedly. Captive Flight Test results show that the proposed modeling strategy has good performance.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.6
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• pp.577-590
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• 2021

In this paper, we theoretically analyzed the self-alignment/navigation performance in the accelerometer resonance state generated by dither motion of ring laser gyroscope in LINS and verified it through simulation. As a result of analysis, it is confirmed that the amplitude of the accelerometer measurement amplified in the accelerometer resonance state is decreased in the process of sampling per the navigation calculation period and that frequency is changed by the aliasing effect too. It was also analysed that the attitude error in self-alignment is determined by the amplitude/frequency of the accelerometer measurement, the gain of the self-alignment loop, and the velocity and position error in the navigation is determined by the amplitude/frequency/phase error of the accelerometer measurement. This analysis and simulation results show that the self-alignment and navigation performance is not be degraded only when the amplification factor of the accelerometer measurement in the accelerometer resonance state is 3 or less

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.2
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• pp.76-85
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• 2010

This paper discusses recent development trends of fiber optic gyroscope (FOG) in space application. Fiber optic gyroscope utilizes Sagnac effect to measure the angular rate of a rotating object in space. Having a rather short development history compared to ring laser gyroscope (RLG), the fiber optic gyroscope, owing to the emerging technologies in fiber optic society and the digital signal processing technique, reveals itself as a noteworthy replacement of the ring laser gyroscope in the space mission. This paper summarizes the current trends of fiber optic gyroscope based on the actual products commercialized in the market over the last decades, while presenting the future development trends of the fiber optic gyroscope in the space exploration.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.459-462
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• 2006

스트랩다운 관성항법장치에 사용되는 대표적인 광학식 자이로인 링레이저 자이로(Ring Laser Gyro ; RLG)는 회전체가 없어 기존의 기계식 자이로가 가지고 있던 g-sensitive 오차가 발생하지 않지만 RLG 내부에 부착되어 링레이저를 반사시키는 기능을 하는 반사경의 산란에 의해 일정 크기의 작은 입력 각속도를 측정하지 못하는 lock-in이 발생한다. 이러한 lock-in을 제거하기 위해 정현파 진동을 RLG 몸체에 인가하며 이 진동에 의하여 자이로 출력에 랜덤워크 성분이 유발되어 RLG 성능저하의 원인이 된다. 본 논문에서는 RLG 랜덤워크에 의한 관성항법장치의 초기정렬 기법에 따른 초기정렬 성능을 분석하고 이에 대한 시뮬레이션 결과를 제시한다.

• 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.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.272-273
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• 2003

링레이저 자이로스코프(Ring Laser Gyroscope-이하 RLG)는 비행기, 유도무기, 선박, 지상무기 등의 관성항법장치(Inertial Navigation System)에 사용되는 각속도 센서로서 항체의 위치와 자세 정보를 제공하는 핵심 구성품 중의 하나이다. 각속도 검출 원리는 삼각형 또는 사각형의 공진기에 He과 Ne을 혼합한 이득매질을 사용하여 서로 반대방향으로 회전하는 두 개의 레이저 빔을 발생시켜서 Sagnac 효과에 의해 외부의 회전 입력을 받을 때 서로 다른 광 경로의 차이로 인한 두 빔의 간섭으로 회전각을 검출한다. (중략)

• 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.