On-board Relative Attitude Determination and Propagation Using Earth Sensor

Abstract

In this paper, we propose methods to determine and propagate relative attitude using an earth sensor. Three-axis attitude determination using the Earth sensor is advantageous in terms of space consumption, but it is a fault that we cannot always use it. By detecting and propagating relative attitude information, we attempt to fill that time gaps. The difficulty is that the spacecraft cannot ignore its own translational movement when it looks at the earth, unlike when it looks at the stars. In this research, the attitude and position estimation method used in computer vision is applied instead of the traditional attitude determination method for spacecrafts used in STT and so on. The algorithms use the movement of a point common to two images taken with a time interval, and the translational movement information of the spacecraft obtained from orbit information. The obtained relative attitude is propagated using a Kalman filter to estimate the absolute attitude. The proposed algorithms are evaluated by numerical simulations. The results are as accurate as small MEMS gyro sensors, suggesting the possibility of being replaceable in the future. Nomenclature m : position on image q : attitude quaternion R : attitude direction cosine matrix t : translational motion direction X : position in space x : position on plane τ : photographing time