• 한국항공우주학회지
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• 제37권1호
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• pp.28-35
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• 2009

본 논문에서는 목표비행체의 궤도운동 특성과 정지궤도에 있는 추적위성의 자세운동 특성을 결합하여 목표비행체를 추적하는 것과 동시에 지상국과 항상 교신할 수 있는 자세틀을 형성할 수 있는 관계식을 유도하였다. 형성되는 자세틀을 유지하기 위해서 추적위성이 고기동 자세변환을 수행할 수 있으므로 고기동에서도 특이점을 갖지 않는 MRP 변수를 사용하였다. 또한, 여러 목표비행체에 대해 연속 추적이 가능하도록 자동으로 자세틀을 변환할 수 있는 관계식을 제시하고 시뮬레이션을 통해 자세틀 유지비행과 연속 추적 성능을 확인하였다. 본 논문에서 제시한 자세틀 유지비행은 고정밀 센서를 이용하지 않아도 지상장비를 통해 목표비행체 궤도만 제공되면 추적위성이 항상 지상과 교신하면서 목표비행체를 추적할 수 있음을 보였다.

• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.203-210
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• 2004

Attitude control law design for spacecraft large angle maneuvers is investigated in this paper. The feedback linearization technique is applied to the design of a nonlinear tracking control law. The output function to be tracked is the quaternion attitude parameter. The designed control law turns out to be a combination of attitude and attitude rate tracking commands. The attitude-only output function, therefore, leads to a stable closed-loop system following the given reference trajectory. The principal advantage of the proposed method is that it is relatively easy to produce reference trajectories and associated controller.

• Transactions on Control, Automation and Systems Engineering
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• 제3권4호
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• pp.257-261
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• 2001

Nonlinear pulse width modulation (PWM) controlled system is considered to achieve control performance of thruster controlled spacecraft. The actual PWM controlled motions occur, very closely, around the average model trajectory. Furthermore nonlinear PWM controller design can be directly applied to thruster controlled spacecraft to determine thruster on-time. Sliding mode control for attitude tracking of three-axis thruster-controlled spacecraft is presented. Simulation results are shown which use modified Rodrigues parameters and sliding mode control law to achieve attitude tracking of a three-axis spacecraft with thrusters.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.461-461
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• 2000

Nonlinear pulse width modulation(PWM) controlled system is considered to achieve control performance of thruster-controlled spacecraft. The actual PWM controlled motions occurs, very closely, around the average model rajectory. Furthermore nonlinear PWM controller design can be directly applied to thruster controlled spacecraft to determine thruster on-time. Sliding mode control for attitude tracking of three-axis thruster-controlled spacecraft is presented. Simulation results are shown which use modified Rodrigues parameters and sliding mode control law to achieve attitude tracking of a three-axis spacecraft with thrusters.

• Journal of Astronomy and Space Sciences
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• 제10권1호
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• pp.1-16
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• 1993

Three typer of spin-axis attitude determination program for the geosynchronous transfer orbit spacecraft are developed. Deterministic closed-from algorithm, batch least-square algorithm and stabilized Kalman filter algorithm are used for implemetation of three programs. EUROSTAR bus model from British Aerospace is used for attitude sensor modelling. Attitude determinations using three programs are performed for the simulated sensor data according to INMARSAT 2-F1 prelaunch mission analysis.

• Journal of Mechanical Science and Technology
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• 제18권1호
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• pp.122-131
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• 2004

A constraint equation-based control law design for large angle attitude maneuvers of flexible spacecraft is addressed in this paper The tip displacement of the flexible spacecraft model is prescribed in the form of a constraint equation. The controller design is attempted in the way that the constraint equation is satisfied throughout the maneuver. The constraint equation leads to a two-point boundary value problem which needs backward and forward solution techniques to satisfy terminal constraints. An observer-based tracking control law takes the constraint equation as the input to the dynamic observer. The observer state is used in conjunction with the state feedback control law to have the actual system follow the observer dynamics. The observer-based tracking control law eventually turns into a stabilized system with inherent nature of robustness and disturbance rejection in LQR type control laws.

• 한국항공우주학회지
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• 제39권8호
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• pp.766-773
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• 2011

항공기용, 함정용 레이더에 비해 비교적 정적인 지상 레이더의 운용 환경을 고려하면 정적인 환경에서 경사면을 측정하는 경사계 등에 사용되는 가속도계로 레이더의 정적인 자세각을 측정할 수 있지만, 바람 및 돌풍 또는 회전하는 안테나의 원심력 등에 의해 동적인 움직임이 발생하게 되는 경우 각가속도가 발생하여 자세각 측정에 오차가 발생할 수 있다. 본 논문에서는 위와 같이 발생한 자세각 측정 오차와 표적 위치에 따른 추적 오차에 대해 분석하고, 가속도계만을 사용한 동적 자세각 측정방법을 제시하고 이에 따라 개선된 추적오차를 시뮬레이션을 통해 결과를 나타내었다.

• Journal of information and communication convergence engineering
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• 제17권3호
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• pp.205-212
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• 2019

Motion tracking and localization devices are an important building block of motion tracking systems in a virtual reality (VR) environment. This study is about improving the accuracy of motion and location for enhancing user immersion in experience type VR environment to position tracking technique. In this study, we propose and test a design of such a device. The module data test of the attitude and heading reference system shows that the implementation with the MPU-9250 sensor is successful and adequate to be used with short operation time. We consider various sensor hardware dependencies of VR, and compare various correction methods and filtering methods to lower the motion to photon (MTP) time that user movement is fully reflected on the display using sensor devices. The Kalman filter is used to combine the accelerometer with the gyroscope in the sensing unit.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1599-1603
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• 2004

Based on the idea that nonlinear PWM controller design can be directly applied to the attitude tracking problem of thruster-controlled spacecraft because it constitutes a sub-class of nonlinear PWM controlled system, nonlinear and output error feedback PWM controlled system is considered to describe the behavior of thruster-controlled spacecraft, and to determine actual thruster on-time which guarantees system stability. A differential geometric approach is utilized to show an asymptotical stability of average PWM system, which finally guarantees the stability of closed loop PWM controlled system. Simulation results show that the motions of PWM controlled system occurs very closely around those of the average model of PWM controlled system.

• 제어로봇시스템학회논문지
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• 제22권1호
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• pp.66-73
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• 2016

An Inertial Measurement Unit (IMU)-based Attitude and Heading Reference System (AHRS) can calculate attitude and heading information with long-term accuracy and stability by combining gyro, accelerometer, and magnetic compass signals. Motivated by this characteristic of the AHRS, this paper presents a Motion-Tracking and Localization (MTL) method for a person or walking robot using multi-AHRSs. Five AHRSs are attached to the two calves, two thighs, and waist of a person/walking robot. Joints, links, and coordinate frames are defined on the body. The outputs of the AHRSs are integrated with link data. In addition, a supporting foot is distinguished from a moving foot. With this information, the locations of the joints on the local coordinate frame are calculated. The experimental results show that the presented MTL method can track the motion of and localize a person/walking robot with long-term accuracy in an infra-less environment.