Autonomous Attitude Control Strategies for a Nanosatellite with a Momentum Wheel

The paper concerns the attitude control system design for a nanosatellite developed in the Aerospace Engineering School Satellite Program at the University of Rome "La Sapienza". According to the philosophy off the university program, which aims to design and build spacecrafts with a small budget, improving the knowledge and the capabilities of the students, this work Is based on an attitude avionics, sensors and actuators, not qualified for space applications. The Control algorithms and strategies are analyzed under the mission constraints that impact the attitude control sub-system structure. In particular the attitude control system is designed to accomplish all the phases of a LEO Sun-synchronous mission, being able to manage their transitions from the satellite injection up to the operative nadir pointing mode, without interaction with the ground. The model reference attitude control presented in the paper have the advantage to reduce the complexity of the control algorithm, since it uses a simple proportional-derivative control scheme with a set of constant gains to force the body reference frame to follow an auxiliary reference frame which motion can be selected as desired. In order to study the control system a simulator has been developed in Simulink environment, and the results are discussed, proving the fulfillment of the mission requirements for the attitude in the operative phases. Copyright © 2006 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.