Star Tracker Sensor Research Articles

Additive Multi-rate Delayed Extended Kalman Filter Attitude Estimation Fusing Gyroscope and Star Tracker Sensors

Additive Multi-rate Delayed Extended Kalman Filter Attitude Estimation Fusing Gyroscope and Star Tracker Sensors

Adaptive Huber-based Kalman filtering for spacecraft attitude estimation

An adaptive Huber-based Kalman filter (AHF) is presented to deal with model error and unknown measurement noise in this article. The adaptive method for model error is obtained using an upper bound for the predicted state error covariance matrix. The measurement noise uncertainty is tackled at each time step by minimizing a criterion function that is original from the Huber technique. A recursive algorithm is also provided to solve the criterion function. The proposed AHF algorithm has been tested in an attitude estimation problem using a gyroscope and star tracker sensors for a single spacecraft in flight simulations in the presence of both model error and non-Gaussian random measurement errors. Simulation results demonstrate the superior performance of the proposed filter compared with the previous filter algorithms. The main contribution of this work can be considered the new application of an existing method.

Adaptive Kalman Filtering for Spacecraft Attitude Estimation

An adaptive Kalman filter (AKF) algorithm is proposed to model and approximation errors in this work. The adaptive algorithm for model and approximation errors is attained by using an upper bound for the state error prediction covariance matrix. The proposed adaptive filter algorithm has been tested in attitude estimation using gyroscope and star tracker sensors for single spacecraft in flight simulations. Simulation results demonstrate the superior performance of the proposed filter as compared to the standard Kalman filter.

Rigid Body Attitude Control Using a Single Vector Measurement and Gyro

Most existing methods for satellite attitude control assume that full knowledge of satellite attitude is available by algebraic manipulation of at least two vector measurements from attitude sensors such as Sun, Earth-horizon, Earth-magnetic or star tracker sensors. Kalman filtering is usually used when only one vector measurement is available, however, asymptotic stability of nonlinear and uncertain dynamics of satellite is not guaranteed in this case. This technical note presents a coupled nonlinear estimator-controller for satellite attitude determination and control by using a 3-axis gyro and a single vector measurement for a fully actuated satellite. We assume that the moment-of-inertia matrix of satellite is unknown. Asymptotic convergence of the satellite attitude and angular velocity to their desired values is proven. Performance of the proposed controller is illustrated in a realistic case study by simulation where a magnetometer is used to provide the single vector measurement.

별추적기의 기술개요와 개발동향

전세계적으로 적용되는 개발개념인 보다 빨리, 더 좋게, 더 값싼 위성을 설계하는 일에 있어 향상된 자세결정시스템을 도입하는 것은 자명한 일이라고 할 수 있다. 오늘날 CCD나 APS 기반의 별추적기는 현존하는 위성의 자세결정용 센서중에서 가장 좋은 정밀도를 제공하고 있다. 본 논문에서는, 별추적기의 기본적인 동작원리와 관련 기술의 개요를 소개함과 동시에 별추적기 개발에서 주요 이슈가 되었던 기술들을 비교 분석한다. 또한 별스캐너로부터 MEMS기술을 적용한 별추적기에 이르기까지, 별추적기의 간추린 역사와 세계 각국에서의 개발현황을 소개한다. In order to accelerate the evolution of faster, better, cheaper spacecraft, it is evident that greatly enhanced general-purpose attitude determination methods are needed Currently, star tracker sensors based on charge coupled devices (CCD) or active pixel sensors(APS) enable one to obtain the best spacecraft attitude estimation among the existing sensors for attitude determination. In this paper, basic principles of star tracker technology are explained including major issues arising in design and development of star tracker. Also, an historical overview and worldwide survey associated with various star trackers from star scanner through microelectromechanical system(MEMS)-based star tracker is offered.

ON-CHIP IMAGE PROCESSING ALGORITHM FOR REAL-TIME CCD-BASED STAR TRACKERS AND WAVEFRONT SENSORS

ABSTRACT In this paper, we describe on-chip and off-chip image procesing algorithms utilizing the internal architect of recently developed CCD sensors to provide high speed readout of selected portions of the imager or accelerated scanning of an entire CCD frame. Image processing time comparable tothe star tracker sensor exposure time and to the characteristic time of the atmospheric fluctuations (10 ms) has been achieved. On-chip image processing is particularly suitable for space or ground-based real-time applications (position determination, tip-tilt correctors, wavefront sensing for adaptive optics systems) where the speed or acquisition and processing data from the "regions of interest" is critical. An example of a star trackers (based on the Texas Instruments TC217 CCD image sensor) for space applications capable of providing real-time multiple position updates with high angular resolution is given and achieved performance is discussed.