Analysis and Control of Attitude Motion for Rapid Regional Scanning Earth Observations

Abstract

Normal Earth observation satellites operate under a nadir-pointing stabilization mode. The effective swath width of observation is limited by the camera’s field-of-view (FOV). In order to achieve continuous and wide swath coverage, a rapid regional scanning observation mode is proposed and analyzed in this paper. Periodic maneuvering about the roll axis is needed to fulfill the mission requirement. A zigzag-like trajectory is developed as a tracking reference trajectory. A sliding mode control algorithm is exploited to achieve high-precision tracking performance. Then, a mixed steering logic utilizing two symmetric-configured control moment gyros (CMG) and three orthogonal-placed magnetic torquers (MTQ) is proposed. CMGs provide large torque for rapid roll maneuvering, and MTQs help to compensate pitch angular velocity bias introduced by the orbital motion. The feasibility of the proposed strategy is verified through numerical simulations. Moreover, this strategy will be further demonstrated on the fourth small satellite, named TSUBAME, designed by the Laboratory of Space Systems at the Tokyo Institute of Technology. TSUBAME is equipped with an ultra-small optical camera designed by the Kimura Laboratory at Tokyo University of Science.