• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.2
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• pp.437-444
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• 2024

The rotational inertial navigation system can provide more accurate navigation information by mounting an IMU (Inertial Measurement Unit) on the gimbal and rotating the gimbal regularly to cancel out the errors of the IMU. However, when an attitude change occurs due to waves, the attitude error is not removed to 0 at the end of one cycle of the rotation procedure and causes a large position error. In this paper, considering this problem, we propose a method of stabilizing the external gimbal by rotating it based on the roll information of the vehicle. Based on simulation, the impact of waves is analyzed and the performance of external gimbal stabilization is verified.

• Journal of Aerospace System Engineering
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• v.12 no.1
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• pp.27-34
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• 2018

In this study, the generating of torque regarding the Control Moment Gyro (CMG) is proportional to the angular velocity of gimbal. This is the case because gimbal affects the attitude control of the satellite directly, and it is necessary to reduce the incidence of torque ripple of gimbal. In this paper, the cause of the torque ripple of gimbal is reviewed and mathematically modeled by assuming the friction imbalance of bearing, the magnetic field and the phase current imbalance of the motor. We are able to confidently estimate the modeling parameters of gimbal disturbance using a constant speed test, and then analyze the influence of applying feedforward control to our modeling. Additionally, the simulation results show that the torque ripple and angular velocity fluctuations are reduced when apply this modeling to the identified study parameters. Finally, we present the disturbance reduction technique using our disturbance modeling.

• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.1-8
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• 2019

The electromagnetic forces generate a torque on the gimbal motor, and changes in the coil current causes torque ripple. This affects the gimbals' speed and results to unstable satellite attitude. It is therefore essential to reduce the torque ripple of the gimble motor with the aim of improving the attitude control accuracy of the satellite. This paper theoretically analyzes the torque generated from the modeling of a motor for general concentrated winding and distributed winding. The prototype was designed and fabricated through selection of the winding that reduces the torque ripple through simulation results. The results of the magnetic fields' theoretical analysis and the back electromotive force of the prototype were compared with the calibrated results for verification of conformity and manufacture of the design. The low-speed test proved that the torque ripple is reduced by improving the speed stability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.992-997
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• 2009

This paper focuses on the calculation of the missile angular velocity under the reduced sensor condition and its verification using the Flight Motion Simulator(FMS). The missile angular velocity is usually measured by the body gyroscopes, but we assume that the inertial sensors on the missile body are in the absence of pitch and yaw gyroscopes. Under this reduced sensor condition, this paper shows the missile angular velocity can be calculated by using the gimbal seeker gyroscope, the roll body gyroscope, the gimbal angle and its rate. The FMS experiment was carried out to verify the proposed algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.281-285
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• 1986

In this paper, the characteristics of disturbance torque of gimbal servo dynamics are studied, and the simulation methods of gimbal servo dynamics and INS error due to angular rate and linear acceleration of vehicle are proposed. In results of the simulation for a specific INS, it is estimated that INS velocity error due to gimbal servo dynamics is nearly proportional to square of vehicle acceleration.

• Journal of Aerospace System Engineering
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• v.13 no.2
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• pp.26-33
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• 2019

Control moment gyro (CMG) employed as satellite actuators, generates a large torque through the steering of its gimbals. Although each gimbal holds a high-speed rotating wheel, the wheel imbalances induces disturbance and degrades the satellite control quality. Therefore, the disturbances ought to be detected and identified as a precaution against actuator faults. Among the method used in detecting disturbances is the state observers. In this paper, we apply a continuous second order sliding mode observer to detect single disturbances/faults in CMGs. Verification of the algorithm is also done on the hardware satellite simulator where four CMGs are installed.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.2
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• pp.13-22
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• 1997

Strapdown inertial navigation system(SDINS) is a navigational instruments necessary to guide and con- trol a free vehicle. In this study, an error analysis of mechanical parts is carried out for manufacturing a dynamically tuned gyroscope. The errors usually come from the tolerance in machining and assembly. In the error analysis, a criterion to be considered during designing and manufacturing is proposed by quanti- tatively analyzing the effect of DTG performance by tolerances. The theory of dynamic balancing is deduced and unbalance is reduced through experiment.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2111-2113
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• 2001

본 논문에서는 MEMS 기술에 의해 제작된 마이크로 가속도계를 위한 신호 검출 및 처리회로를 설계 제작하였으며, 레이트 테이블을 이용한 실험을 통해 제작된 센서 및 신호처리회로의 성능을 시험하였다. 본 논문에서 제시한 가속도계는 입력 가속도에 따라 용량이 변하는 방식으로, 두개의 김블 구조를 가지므로 타축 입력 가속도의 영향을 적게 받는 장점이 있다. 또한 감지전극의 효과적 배치를 통해 감도가 커지도록 설계되었다. 신호검출 및 처리는 여기 신호를 이용한 차분검출방식을 이용하였다. 이 방식은 구성이 복잡한 단점이 있으나, 잡음 신호와 검출 신호를 주파수 영역에서 분리시킬 수 있으며, 기생용량의 영향을 감소시키고 전기적 감도를 증가시키는 장점이 있다. 실험을 통해 제시한 신호검출 및 처리방식을 이용할 경우 가속도계의 성능이 향상되는 것을 확인하였다.