Feed-forward compensation of body-pointing uncertainties for laser communication terminals

Abstract

The performance of the acquisition process in free-space optical communications depends on the quality of the system's a priori attitude knowledge. This paper presents a method to enhance the optical link acquisition process by integrating spacecraft attitude data into the pointing knowledge of the laser communication terminal. Additionally, the self-contained gyroscope sensor of this payload is sampled to propagate movements between updates from the attitude determination and control system to ensure performance during dynamic maneuvers. To enable sensor data fusion, a calibration process is employed, combining a static offline calibration with an online bias estimation that accounts for environmental conditions influencing the gyroscope sensor. The resulting quaternions are used to correct for known body pointing drift around the target through the fast steering mirror. This improvement significantly enhances the success rate of link establishment and reduces the mean acquisition time, thereby increasing the time available for user applications.