Reference Model Variable Structure Output Feedback for Attitude Maneuvers Control of Flexible Spacecrafts

Abstract

In this paper, a new and simple approach for the vibration control of flexible spacecrafts during the attitude maneuvering is proposed. Our control strategy integrates the command input shaping and Reference Model Variable Structure Output Feedback Control (RMVSOFC) techniques. In this method, the input shaper is implemented outside of the feedback loop to achieve the exact elimination of the residual vibration of the reference model. For the feedback loop, a controller is designed to make the closed-loop system follow the reference model at the presence of lumped perturbation. An attractive feature of the proposed RMVSOFC algorithm is the lumped perturbation does not have to satisfy the so-called matching, provided that certain bounds are known beforehand. Computer simulation results are given to demonstrate the effectiveness of this new vibration control technique. Modern spacecrafts often employ large, complex, and lightweight structures, e.g., solar arrays, to achieve increased functionality at a reduced launch cost and provide sustainable energy during the space flight. Orbital operations, such as slewing and pointing maneuvers, will induce the vibrations in these flexible structures. The vibrations can degrade the operational performance. Dynamical models of spacecrafts are also nonlinear and include the rigid and flexible mode interaction. Moreover, the parameters of spacecrafts are not precisely known. The nonlinearity of the dynamical model, parameter uncertainty, and structural vibrations of the flexible parts cause considerable difficulty in the design of control systems for the rotational maneuvers of spacecrafts. The input shaping technique