Large-angle Attitude Maneuver of Spacecraft by using Reaction Control System and Reaction Wheel

Abstract

Missions involving rapid and large-angle attitude maneuvers have been conceived for astronomical and Earth observation satellites in recent years. Since the rotational motion of a spacecraft in such missions is nonlinear, it will be required to design an attitude control system that takes into account nonlinear motion. In light of the necessity for an actuator capable of generating large torque, it is imperative to consider the characteristics of an actuator when designing a control system. Actuators capable of generating large torques include the reaction control system (RCS). RCS provides an on/off input by using the reaction force of fuel injection from the thrusters, it can generate a large torque. In addition, the control system of current application satellites normally uses both RCS and reaction wheel (RW) conventionally used for attitude control. For the above reasons, this paper considers large angle attitude maneuver of spacecraft by a combination of RCS and RW. First, characteristics of RCS and RW are defined, and a design model for controller design is derived based on the relative motion equation of the spacecraft. Next, we design a nonlinear tracking controller so that the closed-loop system becomes input-to-state stable (ISS) using the sliding mode control method. Then, we propose a method to appropriately change RCS injection threshold according to spacecraft attitude by solving an optimization problem. Finally, the effectiveness of the proposed control method is verified by numerical simulations.