• Title/Summary/Keyword: LOS(line of sight) Stabilization

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Analysis of Line of Sight Stabilization Performance based on Direct vs. Indirect of a 2-axis Gimbaled Servo System for Millimeter Wave Seeker (밀리미터파 탐색기 2축 직구동 김발 서보 시스템의 직접 및 간접 시선안정화 성능 분석)

  • Shin, Seungchul;Lee, Sung-Yong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.11
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    • pp.1555-1561
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    • 2018
  • Tracking and detecting targets by the millimeter wave seeker is affected by movement of platform. Stabilization equipments use an inertial sensor to compensate for disturbance of stabilizing gimbal or platform. In the direct line of sight stabilization system, an inertial sensor is mounted on inner gimbal to compensate the disturbance directly, so the performance is excellent and the implementation method is simple. However gimbal design requires somewhat larger volume. Since an inertial sensor is mounted on gimbal base in the indirect line of sight stabilization system, additional space of gimbal is not required for the gimbal design. However, this method does not directly compensate for the disturbance of the line of sight stabilization axis, which can degrade performance. In order to perform the tracking performance, two methods are analyzed for line of sight stabilization performance based on direct and indirect of a 2-axis gimbaled servo system for millimeter wave seeker in this study. The simulation and experimental results validate the performance comparison of two methods.

Real-time Unbalance Moment Compensation Method for Line of Sight(LOS) Stabilization Control System (시선안정화 제어시스템의 실시간 불균형 모멘트 보상기법)

  • Jo, Sihun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.3
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    • pp.323-330
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    • 2016
  • This paper describes real-time unbalance moment compensation method for line of sight(LOS) stabilization control systems. The factors of system inertia, frictions and unbalance moment affect the control accuracy of drive systems that are equipped to on the move(OTM) platforms requiring LOS stabilization function. In case of the unbalance moment among those factors is continuously changed as variation of relative angle between gravity vector and drive torque vector. Then, consideration of the effect in real-time is very complicate. Therefore, its effect should be designed to be minimized, however, designing it almost zero is impossible in real condition. In other words, it is hard to achieve target performance overcoming stability issue of highly unbalanced systems. To solve these problems, this paper proposes calculation method of unbalance moment by using measured sensor data for LOS stabilization control and its use for control compensation. Also, kinematical converting process and control structure for compensation are explained. The effectiveness of the proposed method as variation of unbalance moment is verified under simulation circumstance modeled by assuming LOS control system with 2-axis gimbal structure.

LOS(line-of-sight) Stabilization Control of OTM(on-the-move) Antenna Driven by Geared Flexible Transmission Mechanism (기어와 유연축을 갖는 구동계로 구동되는 OTM 안테나 시선의 안정화 제어)

  • Kang, Min-Sig;Yoon, Wo-Hyun;Lee, Jong-Bee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.10
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    • pp.951-959
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    • 2011
  • In this study, an OTM(on-the-move) antenna which is mounted on ground vehicles and is used for mobile communication between vehicle and satellite while moving was addressed. Since LOS(line-of-sight) of antenna should direct satellite consistently while vehicle moving to guarantee high satellite communication quality, active antenna LOS stabilization is a core technology for OTM antenna. Stabilization of a satellite tracking antenna which consists of 2-DOF gimbals, an elevation gimbal over an azimuth gimbal, was considered in this study. In consideration of driving mechanism which consists of gear train and flexible driving shafts, a two-mass-system dynamic model coupled with vehicle motion was presented. An internal PI-control loop + outer PI-control loop structure has been suggested in order to damp the torsional vibration and stabilize control system. The classical pole-placement method was applied to design control gains. In addition, a vehicle motion compensation control beside of the feedback control loop has been suggested to improve LOS stabilization performances. The feasibility of the proposed control design was verified along with some experimental results.

Adaptive High Precision Control of Lime-of Sight Stabilization System (시선 안정화 시스템의 고 정밀 적응제어)

  • Jeon, Byeong-Gyun;Jeon, Gi-Jun
    • Journal of Institute of Control, Robotics and Systems
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    • v.7 no.1
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    • pp.1155-1161
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    • 2001
  • We propose an adaptive nonlinear control algorithm for high precision tracking and stabilization of LOS(Line-of-Sight). The friction parameters of the LOS gimbal are estimated by off-line evolutionary strategy and the friction is compensated by estimated friction compensator. Especially, as the nonlinear control input in a small tracking error zone is enlarged by the nonlinear function, the steady state error is significantly reduced. The proposed algorithm is a direct adaptive control method based on the Lyapunov stability theory, and its convergence is guaranteed under the limited modeling error or torque disturbance. The performance of the pro-posed algorithm is verified by computer simulation on the LOS gimbal model of a moving vehicle.

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Implementation of a Low-cost Fiber Optic Gyroscope for a Line-of-Sight Stabilization System (Line-of-Sight 안정화 시스템을 위한 저가형 광자이로스코프 구현)

  • Yoon, Yeong Gyoo;Lee, Sang-Min;Kim, Jae Hyung
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.2
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    • pp.168-172
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    • 2015
  • In general, open-loop fiber-optic gyroscopes (FOG) are less stable than closed-loop FOGs but they offer simpler implementation. The typical operation time of line-of-sight (LOS) stabilization systems is a few seconds to one hour. In this paper, a open-loop fiber optic gyroscope (FOG) for LOS applications is designed and implemented. The design goal is aimed at implementing a low cost, compact FOG with low Angle Random Walk (ARW) (< $0.03deg/\sqrt{h}$) and bias instability (< 0.25deg/h). The FOG uses an open-loop all-fiber configuration with 100M PM fiber wound on a small diameter spool. In order to get the design goal, digital signal processing techniques for signal detection, modulation control and compensation are designed and implemented in FPGA.

An Effect of the Inertia Balancer in a Sight Stabilization System (조준경 안정화장치에서 관성밸런서의 영향)

  • 강윤식;김도종;박용운;김광준
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.1028-1032
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    • 1996
  • Stabilization performance of a sight stabilization system can be improved by proper selection of control algorithm and mechanism. In that aspect, in this paper, effects of an inertia balancer are studied. Parameters of the inertia balancer were obtained from the governing equation by assuming there is no external force and friction. Simulation and experimental results show that the inertia balancer contributes significantly to the stabilization of the line of sight(LOS). In particular, it was found that the inertia balancer is more effective as frequency of the disturbance increases.

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Stabilization of elevation for gunner primary sight using variable structure control (가변구조제어에 의한 조준경 고각 안정화)

  • 김중완;이정규;김주상;이만형
    • 제어로봇시스템학회:학술대회논문집
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    • 1990.10a
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    • pp.643-647
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    • 1990
  • Gunner primary sight(GPS) stabilization system lays line of sight(LOS) to find out a target and transmits informations to the fire control system (FCS). In a moving vehicle, accuracy of LOS and FCS depends on the design of GPS and servomechanism system. The heavy vibration of vehicle on the severe off-road environment degenerates the stabilization capability of GPS. In this study, to stabilize of elevation for GPS using the variable structure control, we derived the dynamic equation of GPS system and designed the variable structure controller. Computer simulation results fulfilled the static and dynamic stability of GPS using the variable structure control.

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Identification of Dynamic Characteristics of Gimbals for Line-of-Sight Stabilization Using Signal Compression Method (신호 압축법을 이용한 시선안정화 제어용 짐벌의 동특성 규명)

  • Kim, Moon-Sik;Yoo, Gi-Sung;Yun, Jung-Joo;Lee, Min-Cheol
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.7
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    • pp.72-78
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    • 2008
  • The line-of-sight(LOS) stabilization system is a precision electro-mechanical gimbals assembly for suppressing vibration due to its environment and tracking the target in a desired direction. This paper describes the design of gimbals system to reject the disturbance and to improve stabilization. The controller consists of a DSP with transducer and actuator interfaces. Unknown parameters of the gimbals are estimated by the signal compression method. The cross-correlation coefficient between the impulse response from the assumed model and the one from model of the gimbals is used to obtain the better estimation. The quasi-impulse response through linear element included in the gimbals could be obtained by the signal compression method. The unknown parameter of the linear element could be estimated as comparing the bode plots for impulse response from gimbals with them from model's response.

LOS Stabilization Controller Design of EOTS and Performance Prediction Using Disturbance Model (EOTS 시선안정화 제어기 설계와 외란모델을 이용한 성능예측)

  • Hongwon Kim;Solyi Han;Jungwoong Jang;Kibeom Song
    • Journal of the Korea Institute of Military Science and Technology
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    • v.26 no.1
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    • pp.72-82
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    • 2023
  • The EOTS(Electro Optical Tracking System) must have stabilization performance to provide high-quality images under disturbance environment. In this paper, we present a controller that can minimize the LOS error and has a simple structure. Hence, to evaluate the performance of this controller, analysis in the frequency domain and LOS error measurement are performed. In order to measure the LOS error without a 'rate table' that requires a lot of facility investment, we propose a design method for disturbance model that considers the operating environment of the EOTS. Finally, the performance of the stabilization algorithm is evaluated by the proposed disturbance model.