Terrain Aided Inertial Navigation for Precise Planetary Landing

본 논문에서는 정밀 행성 착륙을 위해 광학센서와 관성항법시스템을 이용한 지형보조 관성항법 시스템을 구현하였다. 또한 측정된 지형 데이터와 사전에 탑재한 지형 데이터간의 특징점 추출, 매칭, 추적의 영상 처리 과정을 수행하였고 이를 통해 특징점의 좌표를 추출할 수 있다. 반복 확장칼만필터를 이용한 항법 시스템은 기존 관성 항법 장치의 항법 오차 누적을 보상하여 보다 정밀한 항법 정보를 제공한다. 이는 향후 착륙선의 유도 및 제어 법칙과 결합하여 정밀 행성 착륙을 위한 시스템 구현에 적용이 가능하다.

MRP 기반 비선형 관측기를 이용한 자이로스코프 보정 및 자세제어 연구

학위논문(석사) - 한국과학기술원 : 항공우주공학전공, 2011.2, [ vi, 53 p. ]This paper covers nonlinear observer design to calibrate error factors of gyro such as bias, scale factor and misalignment. In attitude estimation, gyro should be corrected and Kalman Filter has been widely used in this problem, but it is sensitive to initial guess. Here, nonlinear observer is constructed to resolve the stability of estimation using Lyapunov theorem. Nonlinear Observer has the stability regardless of any initial guess, thus it can replace the filter or provide a stable initial guess for the filter. Also, the controller is integrated with the designed observer and the closed loop system for attitude of the spacecraft is finally completed. The estimation error by observer can affect the stability of the closed loop, thus the effects are analyzed mathematically. The Modified Rodrigues Parameter(MRP), which is recently interested because of its low nonlinearity and non-constrained property, is used for observer and controller design. MRP’s properties permit simplifying the design without any constraint. The designed observer and the closed loop system are simulated to verify the validation.한국과학기술원 : 항공우주공학전공

MRP 기반 비선형 관측기를 이용한 자이로스코프 보정 및 자세제어 연구

학위논문(석사) - 한국과학기술원 : 항공우주공학전공, 2011.2, [ vi, 53 p. ]This paper covers nonlinear observer design to calibrate error factors of gyro such as bias, scale factor and misalignment. In attitude estimation, gyro should be corrected and Kalman Filter has been widely used in this problem, but it is sensitive to initial guess. Here, nonlinear observer is constructed to resolve the stability of estimation using Lyapunov theorem. Nonlinear Observer has the stability regardless of any initial guess, thus it can replace the filter or provide a stable initial guess for the filter. Also, the controller is integrated with the de-signed observer and the closed loop system for attitude of the spacecraft is finally completed. The estimation error by observer can affect the stability of the closed loop, thus the effects are analyzed mathematically. The Modified Rodrigues Parameter(MRP), which is recently interested because of its low nonlinearity and non-constrained property, is used for observer and controller design. MRP’s properties permit simplifying the design without any constraint. The designed observer and the closed loop system are simulated to verify the validation.한국과학기술원 : 항공우주공학전공