High-Order Fully Actuated System Approach-Based Attitude Stabilization for Underactuated Rigid and Flexible Spacecraft

Abstract

This paper addresses the challenge of attitude stabilization for a class of underactuated rigid and flexible spacecrafts by utilizing only two control inputs. The attitude stabilization problem of underactuated spacecraft poses substantial challenges to the High-Order Fully Actuated (HOFA) system approach, due to the fact that it heavily depends on the full actuation characteristics of the system. To circumvent the aforementioned limitation, we first derive a HOFA system for underactuated rigid spacecraft using homogeneity theory and averaged system approach. Subsequently, we design a controller based on the HOFA system approach, which yields a linear closed-loop system. This methodology is then extended to address the simplified attitude stabilization problem of underactuated flexible spacecraft. By utilizing the HOFA system approach in tandem with an observer for estimating modal variables, we propose a control strategy that not only stabilizes the attitude but also actively suppresses elastic vibration. The performance of the proposed control schemes are demonstrated through simulation studies. Note to Practitioners—The motivation of this paper is to address the application of the HOFA system approach to underactuated systems, specifically in underactuated rigid and flexible spacecraft. Due to insufficient control torques, underactuated spacecraft exhibits nonholonomic behavior, which increases the complexity of control. In practical scenarios, modern spacecraft often carries large flexible appendages, which induce sustained vibrations by disturbances and severely affect the attitude stability of spacecraft. The attitude control of underactuated flexible spacecraft is even more challenging. Traditionally, the attitude stabilization of underactuated spacecraft is solved via the first-order state-space method, which is suitable for solving state variables rather than control variables. Due to the limited computational resources on spacecraft, a concise control structure is required. Although the HOFA system approach can provide such a structure, it is designed for fully actuated systems and cannot apply to underactuated systems. To deal with these challenges, this paper proposes a method that transforms an underactuated spacecraft into a fully-actuated system. Building upon the attitude stabilization of underactuated rigid spacecraft, the paper also addresses the attitude stabilization of underactuated flexible spacecraft with vibration suppression. Notably, the proposed method provides a new method for applying the HOFA system approach to underactuated systems, expanding the engineering applications of this approach.