Development and ground evaluation of optical ground station tracking control system of microsatellite RISESAT

摘要

Space Robotic Laboratory (SRL) of Tohoku University is currently developing a 50-kg-class Earth observation microsatellite “RISESAT”, and it is planned to be launched in 2018. In addition to the multiple scientific instruments, RISESAT is equipped with a laser transmission terminal “VSOTA” developed by National Institute of Information and Communications Technology (NICT), and we will conduct optical communication demonstrations between the low-Earth orbit and a ground station. VSOTA eliminated laser emitting direction control mechanism to simplify the system and miniaturize the volume. Therefore, RISESAT has to track an optical ground station with an accuracy of 0.04° by maneuvering the satellite body. To carry out precise attitude control, the ground station transmits a guide laser to the orbit, and RISESAT will detect it with a telescope which is mainly used for Earth observation. In this paper, we propose an attitude control algorithm for an optical ground station tracking with a guide laser. Evaluations of the algorithm were carried out by a simulator “MEVIpS” which is a Hardware-In-the-Loop Simulation (HILS) environment developed by SRL. We confirm that the algorithm satisfies the mission requirements under the influence of sensor noise and computation time limits.